Automatic speed changer

ABSTRACT

A planetary gear unit PR and a clutch C 3  for outputting reduced speed rotation and a clutch C 1  for connecting and disconnecting input of rotation of an input shaft to a sun gear S 2  are located on one axial side of a planetary gear unit PU, and a clutch C 2  for connecting and disconnecting input of rotation of the input shaft to the carrier CR 2  is located on the axially opposite of the planetary gear unit PU. By doing so, as compared to a case wherein, for example, a clutch C 1  and clutch C 2  are both located between a pair of planetary gear units PR and PU, the planetary gear units PR and PU can be located more closely together, and the member that transmits the reduced speed rotation from planetary gear unit PR to planetary gear unit PU can be made shorter. Further, compared to the case wherein, for example, the clutches C 1,  C 2,  C 3  are located on one axial side of the planetary gear units, the construction of the oil lines is simplified.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase Application (35 USC 371) ofPCT/JP2003/017069 and claims priority of Japanese Application No.2002-382531, filed Dec. 27, 2002, the teachings of which areincorporated by reference herein in its entirety, inclusive of thespecification, claims, abstract and drawings.

1. Technical Field

The present invention relates to an automatic transmission for avehicle, and more specifically, to an automatic transmission that canshift between multiple speeds, with the capability of input of reducedspeed rotation to a selected one of the rotary components of a planetarygear unit.

2. Background Art

One type of conventional automatic transmission comprises a planetarygear unit with two rows of linked planetary gears, and planetary gearingthat outputs rotation at a speed reduced from that of the input shaft.See, for example, Japanese Unexamined Patent application Publication No.4-125345 and Japanese Unexamined Patent application Publication No.2000-274498. These publications disclose automatic transmissionsproviding, for example, six forward speeds and one reverse speed, withinput of rotation at a speed reduced by planetary gearing, via a clutch,to one of four rotary components of a planetary gear unit.

In recent years, multi-staging of automatic transmissions has beendesired from the perspective of improved fuel efficiency, due toenvironmental problems and so forth. However, in general, multi-stagingresults in a larger automatic transmission due to the increased numberof components, while from the perspective of ease of mounting on avehicle, a compact automatic transmission is desired.

The above-mentioned conventional automatic transmission comprises twoclutches for inputting the rotation of the input shaft into a rotarycomponent of the planetary gear unit, and planetary gearing for reducingthe speed of rotation of the input shaft for input into the rotarycomponent of the planetary gear unit. However, where the two clutches ora hydraulic servo that controls the engagement of the clutches islocated between the planetary gear unit and the planetary gearing, theunit for transmitting the reduced speed rotation output by the planetarygearing to a rotary component of the planetary gear unit must be axiallyelongated.

The elongated member transmits the reduced speed rotation and a largetorque, and provision of an elongated member that can withstand suchlarge torque requires fabrication from a relatively thick material,which prevents compactness of the automatic transmission. Further, theweight of such a unit is increased, the inertia (inertial force) isincreased, the controllability of the automatic transmission isdecreased and speed change shocks occur more easily.

Further, for example, in order to engage or disengage transfer of thereduced speed rotation to the planetary gear unit from the planetarygearing, a clutch or brake must be provided. In the case that a clutchis provided, this clutch together with the above-mentioned two clutches,total three clutches in all. In general, a clutch has a clutch drum thattransmits the rotation input to the friction plates, and therefore, witha problem such as relative rotation, supply of oil pressure to the oilchamber of the hydraulic servo of the clutch must be from themid-section of the automatic transmission.

However, if the above-described three clutches are located on one axialside of the planetary gear unit for example, oil lines for supplying oilpressure to the three respective hydraulic servos must be provided intriplicate in the mid-section of the automatic transmission for example,and the configuration of the oil lines becomes complicated.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide anautomatic transmission that achieves multi-staging, and yet is reducedin size. Another object of the present invention is to provide anautomatic transmission wherein reduced speed rotation output means and afirst clutch are located on one axial side of the planetary gear unit,and a second clutch is located on the other axial side of the planetarygear unit, so as to provide solution of the above-mentioned problems.

Accordingly, the present invention provides an automatic transmissioncomprising: an input shaft that rotates with the rotation output from adrive source; a planetary gear unit comprised of first, second, third,and fourth rotary components; reduced speed rotation output means forreducing the speed of the input rotation from the input shaft and foroutputting rotation at the reduced speed to the first rotary component;a first clutch that selectively connects the input shaft and the secondrotary component; a second clutch that selectively connects the inputshaft with the third rotary component; and an output unit that outputsthe rotation of the fourth rotary component to a drive wheeltransmission mechanism. The reduced speed rotation output means and thefirst clutch are located on one axial side of the planetary gear unitand the second clutch is located on the other axial side of theplanetary gear unit.

Accordingly, the reduced speed rotation output means and planetary gearunit can be disposed closer to each other in comparison with a casewherein the first clutch and second clutch, for example, are locatedbetween the reduced speed rotation output means and the planetary gearunit, while providing at least five forward speeds forward and onereverse speed. Further, the transmitting member which transmits thereduced speed rotation can be made relatively shorter, thereby enablingthe automatic transmission to be made more compact.

Further, because the transmitting member for transmitting the reducedspeed rotation can be made relatively shorter, it can be morelightweight, and further, because the inertia (inertial force) isreduced, the controllability of the automatic transmission can beimproved, and the occurrence of speed change shock can be reduced.

Further, in the case that the reduced speed rotation output means has aclutch, three clutches in all are required, but compared to the casewherein the three clutches are located on one side of the planetary gearunit, the construction of the oil lines supplying the hydraulic servosof those clutches is easier, the manufacturing process is simplified andthe cost is reduced.

The automatic transmission of the present invention may further includea transmitting member for linking the reduced speed rotation outputmeans and the planetary gear unit, wherein the first clutch is locatedradially inward of the transmitting member.

The reduced speed rotation output means may include an input rotaryelement for receiving input of rotation of the input shaft in acontinuous manner, a fixed element, a reduced speed rotary element, anda third clutch for controlling connection, through the transmittingmember, between the reduced speed rotary element and the first rotarycomponent, wherein the reduced speed rotation is transmitted to thefirst rotary component by engagement of the third clutch.

The automatic transmission of the present invention may have the firstclutch located radially inward of the third clutch.

Accordingly, the third clutch, which must transmit a relatively largetorque at the reduced speed, can be located on the outer circumferentialside, and this third clutch and its hydraulic servo can have a largerdiameter. More specifically, the pressure-receiving area of the oilchamber of the hydraulic servo can be increased, and the capacity fortorque transmission of this third clutch is thereby increased. However,by locating the first clutch, which can have a smaller capacity fortorque transmission compared to the third clutch, on the innercircumferential side, the automatic transmission can be formed morecompact.

The third clutch includes friction members, a drum unit and a hub unitthat links through the friction members with the reduced speed rotarycomponent. The drum unit forms a hydraulic servo with a piston sealed inan oil-tight manner, and links with the first rotary component. Thefirst clutch is located radially inward of the drum unit. The frictionmembers of the third clutch are preferably located radially outward ofthe speed reducing planetary gearing, with the hydraulic servo of thethird clutch disposed adjoining the speed reducing planetary gearing onthe opposite axial side of the planetary gear unit.

The hydraulic servo of a first brake, for braking the first rotarycomponent of the planetary gear unit to which reduced speed rotation isinput, is located radially outward of the hydraulic servo of the thirdclutch.

The intermediate element of the speed reducing planetary gearing may befixed to a first boss extending from one side wall of a case with thehydraulic servo of the third clutch mounted on the first boss. Likewise,the hydraulic servo of the second clutch is located on the outside ofthe second boss that extends from another side wall of the case. Thefirst clutch is located adjoining the planetary gearing and includesfriction members, a hydraulic servo for engaging the friction members,and a drum unit and hub unit integral with the hydraulic servo, whereinthe drum unit is linked with the input shaft.

In one embodiment, the reduced speed rotation output means includes aninput rotary element for receiving input of rotation of the input shaft,a fixable element for being fixed against rotation, a reduced speedrotary element that is linked to the first rotary component at all timesand rotates at the reduced speed, a third clutch for selectivelyconnecting, through the transmitting member, the input shaft and theinput rotary element, and a third brake for fixing the fixable elementagainst rotation, wherein the reduced speed rotation is transmitted tothe first rotary component by engagement of the third clutch and thethird brake. In this embodiment the third clutch may be disposedradially inward of the transmitting member.

The first clutch and the third clutch may be located axially adjacentand radially inward of the transmitting member.

The third clutch includes friction members and a hydraulic servo forengaging the friction members, wherein the hydraulic servo is located onthe side of the speed reducing (second) planetary gear unit axiallyopposite the first planetary gear unit; and wherein a drum unit thatforms the cylinder of the hydraulic servo is linked with the inputshaft.

The hydraulic servo of the third clutch may be located adjoining thehydraulic servo of the first clutch, between the hydraulic servo of thefirst clutch and the friction plates of the third clutch.

The third brake may be located on the side of the second planetary gearunit PR axially opposite the first planetary gear unit PU.

The hydraulic servo of the third brake may be formed in the case.

In yet another embodiment, the reduced speed rotation output meansincludes an input rotary element for receiving input of rotation fromthe input shaft, a fixable element for being fixed against rotation, areduced speed rotary element which rotates at the reduced speed andwhich is connected to the first rotary component at all times, and athird brake for fixing the fixable element against rotation, wherein thereduced speed rotation is transmitted to the first rotary component byengagement of the third brake.

The automatic transmission of the foregoing embodiment achieves sixforward speeds and one reverse speed, and in fourth speed forward thefirst and second clutches are both engaged, that is to say the automatictransmission is directly coupled in fourth speed forward. Therefore, infifth speed forward and sixth speed forward, the gear ratio can be ahigh ratio, so that when the vehicle is running at high speed, theengine speed can be relatively lower, thereby allowing the vehicle torun more quietly at high speed.

The first planetary gear unit is preferably a multiple planetary gearunit, comprising a first sun gear, a long pinion which meshes with thefirst sun gear, a short pinion which meshes with the long pinion, acarrier for rotatably supporting the long pinion and the short pinion, asecond sun gear meshing with the short pinion, and a ring gear meshingwith the long pinion. In such an embodiment the first rotary componentis the first sun gear which receives input of the reduced speed rotationfrom the reduced speed rotation output means, and which can be fixedagainst rotation by engagement of the first brake, the second rotarycomponent is the second sun gear which receives input of the rotation ofthe input shaft upon engagement of the first clutch, the third rotarycomponent is the carrier which receives input of the rotation of theinput shaft upon engagement of the second clutch, and which is fixedagainst rotation by engagement of the second brake, and the fourthrotary component is the ring gear linked to the output member.

The automatic transmission according to another embodiment includes apair of the planetary gear units each comprising a first sun gear, asecond sun gear linked to the first sun gear, a first carrier meshingwith the first sun gear, a second carrier meshing with the second sungear, a first ring gear linked to the second carrier, and a second ringgear meshing with the second carrier. In this embodiment the firstrotary component is the second ring gear which receives input of thereduced speed rotation from the reduced speed rotation output means, andwhich is capable of being fixed against rotation by engagement of thefirst brake and the second rotary component is the first sun gear andthe second sun gear which receive input of the rotation of the inputshaft upon engagement of the first clutch. The third rotary component isthe second carrier and the first ring gear which receive input of therotation of the input shaft upon engaging of the second clutch, andwhich are fixed by engagement of the second brake. The fourth rotarycomponent is a first carrier linked to the output member.

In the foregoing embodiment, in first speed forward, the first clutchand the second brake are engaged; in second speed forward, the firstclutch and the first brake are engaged; in third speed forward reducedspeed rotation is input to the first rotary component from the reducedspeed rotation output means, and the first clutch is engaged; in fourthspeed forward the first clutch and the second clutch are both engaged;in fifth speed forward reduced speed rotation is input to the firstrotary component from the reduced speed rotation output means, and thesecond clutch is engaged; in the sixth speed forward the second clutchand the first brake are engaged; and in the first speed reverse, reducedspeed rotation is input to the first rotary component from the reducedspeed rotation output means, and the second brake is engaged. In thisembodiment six forward speeds and one reverse speed are provided. Infifth speed forward both the first clutch and the second clutch may beengaged to provide a directly coupled state. Therefore, between firstspeed forward and fourth speed forward, the ranges of the gear ratioscan be relatively narrower, and therefore when the vehicle is running ata low to moderate speed, the engine speed can be better optimized, andfuel consumption can be reduced.

Alternatively, in embodiments wherein the planetary gear unit is amultiple planetary gear unit, the first rotary component is the secondsun gear which receives input of the reduced speed rotation of thereduced speed rotation output means; the fixable rotary element is acarrier which receives input of the rotation of the input shaft byengagement of the first clutch, and which is fixed against rotation byengagement of the first brake; the third rotary component is the firstsun gear which receives input of the rotation of the input shaft uponengagement of the second clutch, and which is fixed against rotation byengagement of the second brake; and the fourth rotary component is thering gear.

In the foregoing alternative embodiment, in first speed forward reducedspeed rotation is input to the first rotary component from the reducedspeed rotation output means, and the first brake is engaged; in secondspeed forward, reduced speed rotation is input to the first rotarycomponent from the reduced speed rotation output means, and the secondbrake is engaged; in third speed forward, reduced speed rotation isinput to the first rotary component from the reduced speed rotationoutput means, and the second clutch is engaged; in fourth speed forward,reduced speed rotation is input to the first rotary component from thereduced speed rotation output means, and the first clutch is engaged; infifth speed forward, the first clutch and the second clutch are bothengaged; in sixth speed forward, the first clutch and the second brakeare both engaged; and in first speed reverse, the second clutch and thefirst brake are engaged. Thus, this embodiment also provides six forwardspeeds and one reverse speed.

In the embodiment mentioned above the “fixed element” may be a carrierfixed to the case, optionally, a boss on the interior of the case, andcarrying pinions meshed with the input rotary element and the reducedspeed rotary element. Likewise, the “fixable element” may be a carrierwhich can be fixed against rotation by engagement of a brake and whichcarries pinions meshed with the input rotary element and the reducedspeed rotary element.

The first clutch may be located on the side of the first planetary gearunit axially opposite the speed reducing second planetary gear unit.

Thus, the first clutch engages at relatively low to medium speeds.Accordingly, when this second clutch is disengaged at relatively highspeeds or in reverse, the unit linking this second clutch and the thirdrotary component rotates at a relatively high speed or in the oppositedirection. On the other hand, a case may occur wherein the transmittingmember, that transmits the reduced speed rotation from the reduced speedrotation output means, will rotate at a reduced speed or is engaged, andthe difference in speeds may be great. However, because this secondclutch is located on the side of the first planetary gear unit oppositethe reduced speed rotation output means, the unit rotating at arelatively high speed or in reverse rotation and the unit rotating atthe reduced speed of the reduced speed rotation output means(particularly the transmitting member) can be separated. For example,compared to the case wherein those units are arranged in a multiple axisconfiguration and are in contact, a decrease in efficiency of theautomatic transmission due to relative rotation between these units canbe prevented.

In the foregoing embodiment, the second clutch is engaged in reverse.Accordingly, when the second clutch is engaged in reverse, the reducedspeed rotation unit (particularly the transmitting member) of thereduced speed rotation output means rotates in reverse. In a casewherein the unit linking this second clutch and the third rotarycomponent is rotating at the speed of rotation of the input shaft due tothe second clutch being engaged, the difference in rotational speeds maybe great. However, because the second clutch is located on the side ofthe first planetary gear unit opposite the reduced speed rotation outputmeans, the unit with reverse rotation (particularly the transmittingmember) and the unit that rotates with the rotation of the input shaftcan be separated. As compared to a multiple axis construction whereinthese units are in contact, decrease in efficiency of the automatictransmission due to relative rotation between these units can beavoided.

The first clutch includes friction plates having their inner peripheriessplined to a member linked to the second rotation component, a firstdrum encompassing an hydraulic servo and which is splined on its outercircumferential surface to friction plates, a first piston member forengaging the friction plates, and a first hydraulic servo oil pressurechamber formed by liquid-tight seals between the inner circumferentialsurface of the first piston member and the first drum member. The secondclutch comprises friction plates having their inner edges splined to amember linked to the third rotation component, a second drumencompassing a hydraulic servo and which is splined to the outer edgesof friction plates and which is disposed on the inner circumferentialside of a member linked to the second rotary component, a second pistonmember for engaging the friction plates, and a second hydraulic servooil pressure chamber formed by sealing between the inner circumferentialsurface of the second piston member and the input shaft, and between theouter circumference surface and the second drum member.

The output member may be disposed axially between the first planetarygear unit and the reduced speed rotation output means.

Accordingly, the output unit can be located in approximately the axialcenter of the automatic transmission. Thus, when the automatictransmission is mounted on the vehicle, enlargement towards the rear(when the end receiving the input from the drive source is the “front”)becomes unnecessary because the output member is mounted to mate withthe drive wheel transmission device. Because of this, particularly inthe case of a FF vehicle, interference with the front wheels is reduced,and the mountability on a vehicle is improved, for example, the steeringangle is greatly increased.

The output member may be located axially between the planetary gear unitand the second clutch. Accordingly, the planetary gear unit and thereduced speed rotation output means can be arranged even closertogether, and the transmitting member can be further shortened.

The reduced speed rotation output means may be in the form of a speedreducing second planetary gear unit, more specifically, a double pinionplanetary gear unit, wherein the speed reducing second planetary gearunit, the first planetary gear unit, and the output member, are arrangedcoaxially with the input shaft.

A differential unit outputs rotation to the drive wheels, a countershaft unit is engaged with the differential unit, and the output membermay be a counter gear meshing with the counter shaft unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of an automatic transmissionaccording to a first embodiment;

FIG. 2 is a table of operations of the automatic transmission of thefirst embodiment;

FIG. 3 is a speed line diagram for the first embodiment;

FIG. 4 is a schematic cross-sectional view of an automatic transmissionaccording to a second embodiment;

FIG. 5 is a schematic cross-sectional view of an automatic transmissionaccording to a third embodiment;

FIG. 6 is a table of operations of the automatic transmission of thethird embodiment;

FIG. 7 is a speed line diagram for the automatic transmission of thethird embodiment;

FIG. 8 is a schematic cross-sectional view of an automatic transmissionaccording to a fourth embodiment;

FIG. 9 is a table of operations for the automatic transmission of thefourth embodiment;

FIG. 10 is a speed line diagram for the automatic transmission of thefourth embodiment;

FIG. 11 is a schematic cross-sectional view of an automatic transmissionaccording to a fifth embodiment;

FIG. 12 is a schematic cross-sectional view of an automatic transmissionof a sixth embodiment;

FIG. 13 is a schematic cross-sectional view of an automatic transmissionof a seventh embodiment;

FIG. 14 is a schematic cross-sectional view of an automatic transmissionaccording to an eighth embodiment;

FIG. 15 is a schematic cross-sectional view of an automatic transmissionaccording to a ninth embodiment;

FIG. 16 is a schematic cross-sectional view of an automatic transmissionaccording to a tenth embodiment;

FIG. 17 is a schematic cross-sectional view of an automatic transmissionof an eleventh embodiment;

FIG. 18 is a schematic cross-sectional view of an automatic transmissionaccording to a twelfth embodiment;

FIG. 19 is a schematic cross-sectional view of an automatic transmissionaccording to a thirteenth embodiment;

FIG. 20 is a schematic cross-sectional view of an automatic transmissionaccording to a fourteenth embodiment;

FIG. 21 is a schematic cross-sectional view of an automatic transmissionaccording to a fifteenth embodiment;

FIG. 22 is a table of operations of the automatic transmission of thefifteenth embodiment,

FIG. 23 is a speed line diagram for the automatic transmission of thefifteenth embodiment;

FIG. 24 is a schematic cross-sectional view of an automatic transmissionaccording to a sixteenth embodiment;

FIG. 25 is a table of operations of the automatic transmission of thesixteenth embodiment;

FIG. 26 is a speed line diagram for the automatic transmission of thesixteenth embodiment;

FIG. 27 is a schematic cross-sectional view of an automatic transmissionaccording to a seventeenth embodiment;

FIG. 28 is a table of operations of the automatic transmission of theseventeenth embodiment;

FIG. 29 is a speed line diagram for the automatic transmission of theseventeenth embodiment;

FIG. 30 is a schematic cross-sectional view of an automatic transmissionaccording to an eighteenth embodiment;

FIG. 31 is a table of operations of the automatic transmission of theeighteenth embodiment;

FIG. 32 is a speed line diagram for the automatic transmission of theeighteenth embodiment;

FIG. 33 is a schematic cross-sectional view of an automatic transmissionof a nineteenth embodiment;

FIG. 34 is a table of operations of the automatic transmission of thenineteenth embodiment;

FIG. 35 is a speed line diagram for the automatic transmission of thenineteenth embodiment;

FIG. 36 is a schematic cross-sectional view of an automatic transmissionaccording to a twentieth embodiment;

FIG. 37 is a table of operations of the automatic transmission of thetwentieth embodiment;

FIG. 38 is a speed line diagram for the automatic transmission of thetwentieth embodiment;

FIG. 39 is a schematic cross-sectional view of an automatic transmissionaccording to a twenty-first embodiment;

FIG. 40 is a schematic cross-sectional view of an automatic transmissionaccording to a twenty-second embodiment;

FIG. 41 is a schematic cross-sectional view of an automatic transmissionaccording to a twenty-third embodiment;

FIG. 42 is a schematic cross-sectional view of an automatic transmissionaccording to a twenty-fourth embodiment; and

FIG. 43 is a schematic cross-sectional view of an automatic transmissionaccording to a twenty-fifth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A first embodiment of the present invention will be described withreference to FIG. 1 through FIG. 3 below. FIG. 1 shows an automatictransmission 1 ₁ according to the first embodiment of the presentinvention that is particularly well suited for a FF (front engine, frontwheel drive) vehicle. A case includes a torque converter housing (notillustrated) and a transmission case 3 which houses the automatictransmission 1 ₁, a counter shaft unit (drive wheel transmission device)(not illustrated) and a differential unit (drive wheel transmissiondevice).

The torque converter is centered on the axis of input shaft 2 of theautomatic transmission 1 ₁, which is on the same axis as the outputshaft of the engine (not illustrated). Further, the above-mentionedcounter shaft unit includes a counter shaft (not illustrated) aligned onan axis parallel to the input shaft 2, and the above-mentioneddifferential unit has a lateral axle aligned parallel to the countershaft.

FIG. 1 shows, arranged along the input shaft 2, a first planetary gearunit PU and a second planetary gear unit (reduced speed rotation outputmeans) PR. The first planetary gear unit PU is a multiple type planetarygear unit which includes a sun gear (the second rotary component) S2, acarrier (the third rotary component) CR2, a ring gear (the fourth rotarycomponent) R3, and a sun gear (the first rotary component) S3, as thefour rotary components. The carrier CR2 has a long pinion PL that mesheswith the sun gear S3 and the ring gear R3, and a short pinion PS thatmeshes with the sun gear S2, wherein the pinions are also meshed to oneanother. Further, the second planetary gear unit PR is a so-calleddouble planetary gear unit that has a carrier CR1 which rotatablysupports a pinion Pb meshing with a ring gear R1 and a pinion Pa meshingwith a sun gear S1, wherein the pinions also mesh one with another.

Arranged on the input shaft 2 are a multi-disc clutch (first clutch) C1,which comprises a hydraulic servo 11, friction plates 71, a clutch drum21, and a hub unit 22 linked to sun gear S2 on the inner circumferentialside; and a multi-disc clutch (third clutch) C3, which includes ahydraulic servo 13, friction plates 73, and a clutch drum 25 on theouter circumferential side. Further, located radially outward of thedrum member 25 is a multi-disc brake B1 (first brake) which has ahydraulic servo 14 and friction plates 74.

Hydraulic servo 11 includes a piston unit b for engaging the frictionplates 71, a drum 21 that has a cylinder unit e, an oil chamber(hereafter, simply “oil chamber”) “a” formed by seal rings f and ginterposed between piston unit b and cylinder unit e, a return spring cthat biases piston unit b toward oil chamber “a”, and a return plate dthat bears the force of return spring c.

In the descriptions to follow, each hydraulic servo shall be consideredas being constructed similarly, i.e., as having an oil chamber “a”, apiston unit b, a return spring c, a return plate d, a cylinder unit e,and seal rings f and g, and, as such, descriptions thereof will not berepeated.

The oil chamber “a” of this hydraulic servo 11 is connected to an oilline 2 a which is formed on the input shaft 2, and this oil line 2 a isconnected to the oil line 91 of the boss 3 a which is in the form of asleeve surrounding the input shaft 2. Further, this oil line 91 isconnected to an oil pressure control unit, not illustrated. In otherwords, due to the above-mentioned hydraulic servo 11 being mounted onthe input shaft 2, an oil supply path from the oil pressure controlunit, not illustrated, to the oil chamber “a” of the hydraulic servo 11is connected simply by providing one set of seal rings 81 between theboss 3 a and the input shaft 2.

Further, the oil chamber “a” of the above-mentioned hydraulic servo 13is directly connected to an oil line 92 of the above-mentioned boss 3 a,and this oil line 92 is connected to an oil pressure control unit, notillustrated. Thus, the hydraulic servo 13 has its oil chamber “a”connected to the oil pressure control unit simply by providing one setof seal rings 80 between the boss 3 a and the drum 25.

The input shaft 2 is connected to the above-mentioned drum 21, and theinner circumferential surface of this drum 21 is splined to the frictionplates 71 of the clutch C1 which is operated by the hydraulic servo 11.The friction plates 71 of clutch C1 are intermeshed with friction platessplined to the hub unit 22 which is connected to the sun gear S2.

The drum 25 is rotatably supported by the boss 3 a and the outercircumferential surface of a front portion of this drum 25 is splined tofriction plates 74 of the brake B1 which can be engaged by the hydraulicservo 14. The inner circumferential surface of the front portion of thisdrum 25 is splined to the friction plates 73 of the clutch C3 which isoperated by the hydraulic servo 1. The friction plates 73 areintermeshed with friction plates splined to the ring gear R1.

The carrier CR1 supports a pinion Pa and a pinion Pb, pinion Pb mesheswith the above-mentioned ring gear R1, and pinion Pa meshes with the sungear S1 which is connected to the input shaft 2. This carrier CR1 issecured to the boss 3 a of via a side plate, and ring gear R1 issupported by a supporting plate 26 which, in turn, is rotatablysupported by the boss 3 a.

Further, the above-mentioned drum 25 receives, via a linking member(hereafter, also referred to as “transmitting member”) 30, the rotationof the ring gear R1. At one end of this transmitting member 30 isconnected the sun gear S3 of the first planetary gear unit PU.

On the other side of the input shaft 2 (left in diagram) is a multi-discclutch (second clutch) C2 that has an hydraulic servo 12, frictionplates 72, clutch drum 23, and a hub unit 24 linked to a carrier CR2.

Oil chamber “a” of hydraulic servo 12 is connected to an oil line 2 bwhich is formed on the above-mentioned input shaft 2, and this oil line2 b is connected to the oil line 93 in the boss 3 b which is also formedas a sleeve around the input shaft 2. This oil line 93 is connected toan oil pressure control unit, not illustrated. Thus, an oil line fromthe oil pressure control unit is connected to the oil chamber “a” of thehydraulic servo 12 simply by providing one set of seal rings 82 betweenthe input shaft 2 and the drum 23.

The inner circumferential surface of a front portion of drum 23 issplined to the friction plates 72 of the clutch C2 which is operated bythe hydraulic servo 12. The friction plates 72 of this clutch C2 areintermeshed with friction plates splined to the hub unit 24, and thishub unit 24 is connected to the side plate of the carrier CR2. Radiallyoutward of the planetary gear unit PU is a multi-disc brake (secondbrake) B2 that has an hydraulic servo 15, friction plates 75, and a hubunit 28. The side plate of the carrier CR2 of this planetary gear unitPU is connected to a hub unit 28 to which are splined the frictionplates 75 of the above-mentioned brake B2. This hub unit 28 is alsoconnected to the inner race of a one-way clutch F1. The ring gear R3meshes with the long pinion PL of carrier CR2, has one end connected toa linking member 27, and is linked to the counter gear 5 via thislinking member 27.

As described above, the second planetary gear unit PR, the clutch C1 andthe clutch C3 are located at one axial end of the first planetary gearunit PU and the clutch C2 is located on the opposite axial side. Thecounter gear 5 is located between the second planetary gear unit PR andthe first planetary gear unit PU. Further, the clutch C1 is disposedradially inward of the clutch C3, and, particularly, inward of a sectionof the transmitting member 30 that transmits the output thereof.Further, the brake B1 is located radially outward of the secondplanetary gear unit PR, and the brake B2 is located radially outward ofthe first planetary gear unit PU.

Operations of automatic transmission 1 ₁ will now be described, withreference to FIG. 1, FIG. 2, and FIG. 3 below. The vertical axes of thespeed line diagram illustrated in FIG. 3 indicate the rotational speedsof each rotary component, and the horizontal axis indicates thecorresponding gear ratio for these rotary components. In the planetarygear unit PU section of this speed line diagram, the vertical axis tothe farthest right side of FIG. 3 corresponds to sun gear S3, and movingto the left within the diagram, the vertical axes correspond to thecarrier CR2, the ring gear R3, and the sun gear S2. Further, in thesecond planetary gear unit PR section of this speed line diagram, thevertical axis to the farthest right side of FIG. 3 corresponds to sungear S1, and moving to the left within the diagram, the vertical axescorrespond to the ring gear R1 and the carrier CR1. Further, the widthsbetween these vertical axes are inversely proportional to the number ofteeth of each of the sun gears S1, S2, S3, and to the number of teeth ofeach of the ring gears R1, R3. The dotted horizontal line within thediagram represents the rotation transmitted by the transmitting member30.

As illustrated in FIG. 1, the rotation of input shaft 2 is input to thesun gear S2, by engaging the clutch C1. The rotation of input shaft 2 isinput to the above-mentioned carrier CR2, by engaging the clutch C2, andthis carrier CR2 can be fixed against rotation by engagement of brakeB2. Further, the rotation is limited to one direction by the one-wayclutch F1. The sun gear S3 can be fixed against rotation by engagementof the brake B1.

The above-mentioned sun gear S1 is connected to the input shaft 2 so asto receive as input the rotation thereof. The carrier CR1 is fixed tothe case 3 and, therefore the ring gear R1 rotates at a reduced speed.Further, by engaging the clutch C3, the reduced speed rotation of thisring gear R1 is input to the sun gear S3.

Also, the rotation of the ring gear R3 is output to the counter gear 5,and is output to the drive wheels via this counter gear 5, a countershaft unit not illustrated, and a differential unit.

In first speed forward within D (drive) range, as illustrated in FIG. 2,the clutch C1 and the one-way clutch F1 are engaged. Then, asillustrated in FIG. 3, the rotation of input shaft 2 is input to the sungear S2 via the clutch C1, and the rotation of the carrier CR2 islimited to one direction (the forward rotation direction). Further, therotation of input shaft 2 that is input to the sun gear S2 is output tothe ring gear R3 via the fixed carrier CR2, and the forward rotation forfirst speed forward is output from the counter gear 5. When downshifting(coasting), the brake B2 is engaged and carrier CR2 is thereby fixed,and the above-described state of first speed forward is maintained whilepreventing the forward rotation of carrier CR2. In this first speedforward, because the one-way clutch F1 allows only forward rotation ofthe carrier CR2, switching from a non-driving range to a driving rangeand achieving the first speed forward can be accomplished more smoothlyby the automatic engaging of the one-way clutch.

In second speed forward within the D (drive) range, as illustrated inFIG. 2, the clutch C1 and the brake B1 are engaged. Then, as illustratedin FIG. 3, the rotation of input shaft 2 is input to the sun gear S2 viathe clutch C1, and the sun gear S3 is fixed by engagement of the brakeB1. By doing so, the carrier CR2 rotates at a slightly reduced speed,and the rotation of input shaft 2 that was input in the sun gear S2 isoutput to the ring gear R3 via the carrier CR2 at this reduced speed,and the forward rotation for second speed forward is output from thecounter gear 5.

In third speed forward within the D (drive) range, as illustrated inFIG. 2, the clutch C1 and the clutch C3 are engaged. Then, asillustrated in FIG. 3, the rotation of input shaft 2 is input to the sungear S2 via the clutch C1. Further, by the input of the rotation of theinput shaft 2 to the sun gear S1 and the fixed state of carrier CR1, thering gear R1 is rotated at a reduced speed, and the reduced speedrotation of ring gear R1 is output to the sun gear S3 via the clutch C3and the transmitting member 30. The carrier CR2 rotates at a speedslightly reduced as compared to that of sun gear S3 because of therotation of the input shaft 2 input to the sun gear S2 and the reducedspeed of the sun gear S3. Further, the rotation of input shaft 2 that isinput to the sun gear S2 is output to the ring gear R3 via the carrierCR2 at this reduced speed, and the forward rotation for third speedforward is output from the counter gear 5. In this case, because the sungear S3 and the ring gear R1 are rotating at a reduced speed, theabove-mentioned transmitting member 30 transmits a relatively largetorque.

In fourth speed forward within the D (drive) range, as illustrated inFIG. 2, the clutch C1 and the clutch C2 are engaged. Then, asillustrated in FIG. 3, the rotation of input shaft 2 is input to the sungear S2 via the clutch C1, and into the carrier CR2 via the clutch C2.Therefore, by input of the rotation of the input shaft 2 to the sun gearS2 and the rotation of input shaft 2 input to the carrier CR2, a stateof directly coupled rotation is established wherein the rotation of theinput shaft 2 is output as is to the ring gear R3, and the forwardrotation for fourth speed forward is output from the counter gear 5.

In fifth speed forward within the D (drive) range, as illustrated inFIG. 2, the clutch C2 and the clutch C3 are engaged. Then, asillustrated in FIG. 3, the rotation of input shaft 2 is input to thecarrier CR2 via the clutch C2. Further, by input of the rotation of theinput shaft 2 to the sun gear S1 and the fixed state of carrier CR1, thering gear R1 rotates at a reduced speed, and the reduced speed rotationof this ring gear R1 is output to the sun gear S3 via the clutch C3 andthe above-mentioned transmitting member 30. Overdrive rotation is outputto the ring gear R3 from the sun gear S3 and the carrier CR2, and theforward rotation for fifth speed forward is output from the counter gear5. In this case, similar to the above-mentioned case of third speedforward, due to rotation of the sun gear S3 and the ring gear R1 at areduced speed, the above-mentioned transmitting member 30 transmits arelatively large torque.

In sixth speed forward within the D (drive) range, as illustrated inFIG. 2, the clutch C2 and the brake B1 are engaged. Then, as illustratedin FIG. 3, the rotation of the input shaft 2 is input to the carrier CR2via the clutch C2, and the sun gear S3 is fixed by engagement of thebrake B2. This produces overdrive rotation (greater than that of theabove-mentioned fifth speed forward), from the rotation of the inputshaft 2 input to the carrier CR2 and the fixed state of sun gear S3,which overdrive rotation is output to the ring gear R3, and the forwardrotation for sixth speed forward is output from the counter gear 5.

In first speed reverse within an R (reverse) range, as illustrated inFIG. 2, the clutch C3 and the brake B2 are engaged. Then, as illustratedin FIG. 3, the ring gear R1 rotates at reduced speed based on therotation of input shaft 2 input to the sun gear S1 and the fixed stateof carrier CR1, and the reduced speed of this ring gear R1 is output tothe sun gear S3 via the clutch C3 and the above-mentioned transmittingmember 30. Further, the carrier CR2 is fixed by engaging the brake B2.Then, the reduced speed rotation of the sun gear S3, with carrier CR2fixed, is output to the ring gear R3 as reverse rotation and is outputas first speed reverse from the counter gear 5. In this case, similar tothe case of the above-mentioned third speed forward or fifth speedforward, since the sun gear S3 and the ring gear R1 are rotating at areduced speed, the above-mentioned transmitting member 30 transmits arelatively large torque.

In the P (parking) range and the N (neutral) range, clutch C1, clutchC2, and clutch C3 are released, the input shaft 2 is disconnected fromthe the counter gear 5, and the automatic transmission 1 ₁ as a whole isin an idle state (neutral state).

As described above, in the automatic transmission 1 ₁ of the presentinvention, due to the location of the secondary planetary gear unit PRand the clutch C1 on one axial side of the first planetary gear unit PU,and the clutch C2 being located on the other axial side of the planetarygear unit PU, the second planetary gear unit PR and the first planetarygear unit PU can be arranged more closely together, as compared to thecase wherein for example two clutches C1 and C2 are located between thesecond planetary gear unit PR and the first planetary gear unit PU, andthe transmitting member 30 for transmitting reduced speed rotation canbe relatively shorter. In this manner, the automatic transmission can bemade more compact and lightweight. Further, because the inertia(inertial force) can be reduced, the controllability of the automatictransmission can be increased, and the occurrence of speed change shockcan be reduced. Further, compared to the case wherein three clutches C1,C2, C3 are located on one side of the first planetary gear unit PU, theoil lines (for example, 2 a, 2 b, 91, 92, 93), that supply the hydraulicservos 11, 12, and 13 of these clutches C1, C2, C3, are more easilyconstructed, the manufacturing process is simplified and the cost isreduced.

Further, due to the hydraulic servos 11 and 12 being provided on theinput shaft 2, one set of seal rings 81 and 82 serves to form aconnection with the oil lines 2 a and 2 b provided within input shaft 2,and therefore oil can be supplied to the oil chamber “a” of thehydraulic servos 11 and 12 without providing seal rings between, forexample, the input shaft 2 and the hydraulic servos 11 and 12. Further,the hydraulic servo 13 can receive a supply of oil directly from theboss 3 a, i.e. without passing through other units, merely by providingone set of seal rings 80. Therefore, the hydraulic servos can beconnected to the oil supply simply by providing one set of seal rings 81and 82, 80 each for each of the hydraulic servos 11, 12, and 13, slidingresistance from the seal rings can be minimized, and therefore theefficiency of the automatic transmission can be improved.

Further, since the clutch C1 is located radially inward of the clutchC3, the clutch C3, which must transmit a relatively large torque inorder to transmit the reduced speed rotation, can be located at theouter side and therefore this clutch C3 and its hydraulic servo 13operator can have an increased diameter. Thus, the pressure-receivingarea of the oil chamber “a” of the hydraulic servo 13 can be enlarged,and the torque transmission capacity of this clutch C3 can be increased.By designing the clutch C1 to have a smaller torque transmissioncapacity as compared to the clutch C3, the automatic transmission can bemade more compact.

Further, because the counter gear 5 is located axially between the firstplanetary gear unit PU and the second planetary gear unit PR, thecounter gear 5 can be located in approximately the axial center of theautomatic transmission. Thus, for example, when the automatictransmission is mounted on the vehicle, enlargement toward the rear(when the side which receives input from the drive source is the“front”) is not necessary because the counter gear 5 is mounted to matethe drive wheel transmission device. Because of this, particularly inthe case of a FF vehicle, interference with the front wheels is reduced,and the steering angle can be greatly increased, for example.

The automatic transmission 1 ₁ of the first embodiment is directlycoupled in fourth speed forward. Therefore, at fifth speed forward andsixth speed forward, the gear ratio can be a higher ratio and, when thevehicle is running at a high speed, the engine speed can be relativelylower, which allows the vehicle to run more quietly at a high speed.

Second Embodiment

A second embodiment, which is a partial modification of the firstembodiment, will now be described, with reference to FIG. 4 which showsan automatic transmission 1 ₂ as having its input and output sidesreversed from the automatic transmission 1 ₁ of the first embodiment.Further, the operations of the first through sixth forward speeds andthe first reverse speed of 1 ₂ of the second embodiment are similar tothose of the automatic transmission 1 ₁ of the first embodiment (seeFIG. 2 and FIG. 3). Components of the second embodiment that are thesame as those of the first embodiment are denoted by the same referencenumerals, and description thereof omitted, except for those componentspartially modified.

As with the first embodiment, in this second embodiment, due to thesecond planetary gear unit PR and the clutch C1 being located on oneside of the first planetary gear unit PU, and the clutch C2 beinglocated on the other axial side of the planetary gear unit PU, thesecond planetary gear unit PR and the first planetary gear unit PU canbe placed more closely together, as compared to the case wherein, forexample, the two clutches C1 and C2 are located between the secondplanetary gear unit PR and the first planetary gear unit PU. Thus, thetransmitting member 30 which transmits the reduced speed rotation can berelatively shorter. By doing so, the automatic transmission can be mademore compact and more lightweight. Further, because the inertia(inertial force) can be reduced, the controllability of the automatictransmission can be increased, and the occurrence of speed change shockcan be reduced. Further, compared to the case where three clutches C1,C2, C3 are located on one side of the first planetary gear unit PU, theoil lines (for example, 2 a, 2 b, 91, 92, 93) that supply the hydraulicservos 11, 12, and 13 of these clutches C1, C2, C3 can be more easilyconstructed, the manufacturing process can be simplified, and the costsbrought down.

Further, since the hydraulic servos 11 and 12 are mounted on the inputshaft 2, one set of seal rings 81 and 82 serves to seal the case 3 andto establish a connection with the oil lines 2 a and 2 b within inputshaft 2, and therefore oil can be supplied to the oil chambers “a” ofthe hydraulic servos 11 and 12 without providing seal rings between, forexample, the input shaft 2 and the hydraulic servos 11 and 12. Further,hydraulic servo 13 can receive a supply of oil directly from the bossunit 3 a, i.e. without that supply passing through other units, forexample, by provision of one set of seal rings 80. Therefore, the oilsupply can be connected by provision of one set of seal rings 81 and 82,80, respectively, for each of the hydraulic servos 11, 12, and 13,sliding resistance from the seal rings can be minimized, andaccordingly, the efficiency of the automatic transmission can beimproved.

As in the first embodiment, because the clutch C1 is located radiallyinward of the clutch C3, the clutch C3, which must transmit a relativelylarge torque in order to transmit the reduced speed rotation, can bearranged at the outer circumference. Therefore, this clutch C3 and itspressure servo 13 can have an increased diameter, the pressure-receivingarea of its oil chamber can be enlarged, and its torque transmissioncapacity can be increased. Again, by designing the clutch C1 to have asmaller torque transmission capacity as compared to the clutch C3, theautomatic transmission can be made more compact.

Further, because the counter gear 5 is located axially between the firstplanetary gear unit PU and the second planetary gear unit PR, thecounter gear 5 can be located in approximately the axial center of theautomatic transmission. With this second embodiment also, enlargementtoward the rear (when the end which receives input from the drive sourceis the “front”) is not necessary because the counter gear 5 is mountedto mate with the drive wheel transmission device. Because of this,particularly in the case of a FF vehicle, interference with the frontwheels is reduced, mountability on a vehicle is improved, and thesteering angle is greatly increased.

Further, the automatic transmission 1 ₂ according to the secondembodiment is directly coupled in fourth speed forward. Therefore, atfifth speed forward and sixth speed forward, the gear ratio can be ahigh ratio, and when the vehicle is running at a high speed, the enginespeed can be relatively less, thus allowing the vehicle to run morequietly at a high speed.

Third Embodiment

A third embodiment, which is a partial modification of the firstembodiment, will now be described with reference to FIG. 5 through FIG.7. Components of the third embodiment that are the same as the firstembodiment are denoted by the same reference numerals, and descriptionthereof omitted, except for those components partially modified.

As shown in FIG. 5, the automatic transmission 1 ₃ of the thirdembodiment is modified with respect to the configuration of the secondplanetary gear unit PR and the clutch C3, as compared to the automatictransmission 1 ₁ of the automatic transmission of the first embodiment(see FIG. 1).

In this automatic transmission 1 ₃, the clutch C3 is located on theplanetary gear unit PU side (left side of diagram) of the secondplanetary gear unit PR. The inner circumferential surface of a frontportion of the drum 25 of clutch C3 is splined to the friction plates 73which are intermeshed with friction plates splined to the hub unit 26.Further, the drum 25 is connected to the input shaft 2, and the hub unit26 is connected to the sun gear S1.

The side plate of the carrier CR1 is fixed to and supported by the case3. Also, the ring gear R1 is connected to the transmitting member 30,and the outer circumferential surface of the transmitting member 30 issplined to the friction plates 74 of the brake B1, and this transmittingmember 30 is connected to the sun gear S3.

The oil chamber of hydraulic servo 13 for the clutch C3 is connected toan oil line 2 c which is formed in parallel with oil line 2 a on theabove-mentioned input shaft 2, and this oil line 2 c is connected to theoil line 92 of the boss 3 a which, in turn, is connected to an oilpressure control unit, not illustrated. In other words, because thehydraulic servos 11 and 13 are mounted on input shaft 2, oil supply fromthe oil pressure control unit, not illustrated, to their oil chamberscan be connected simply by providing seal rings 81 between the boss 3 aof and the input shaft 2.

Operations of the automatic transmission 1 ₃ of the third embodimentwill now be described below, with reference to FIG. 5, FIG. 6, and FIG.7. Similar to the first embodiment, the vertical axes of the speed linediagram in FIG. 7 indicate the speed of each rotary component, and thehorizontal axis indicates the corresponding gear ratio of the rotarycomponents. In the planetary gear unit PU section of this speed linediagram, the vertical axis to the farthest right side of FIG. 7corresponds to the sun gear S3, and moving to the left within thediagram, the vertical axes correspond to the carrier CR2, the ring gearR3, and the sun gear S2. In the planetary gear unit PR section of thisspeed line diagram, the vertical axis to the farthest right side of FIG.7 corresponds to the sun gear S1, and moving to the left within thediagram, the vertical axes correspond to the ring gear R1 and thecarrier CR1. Further, the widths between these vertical axes areinversely proportional to the number of teeth of each of the sun gearsS1, S2, S3, and to the number of teeth of each of the ring gears R1, R3.Also, the horizontal dotted line in the diagram represents the rotationtransmitted by the transmitting member 30.

As FIG. 5 illustrates, the rotation of input shaft 2 is input to the sungear S1 by engaging the clutch C3. Further, the carrier CR1 is fixed tothe case 3, and the ring gear R1 rotates at a reduced speed based on therotation of input shaft 2 which is input to this sun gear S1. In otherwords, by engaging the clutch C3 the reduced speed rotation of the ringgear R1 is input to the sun gear S3 via the transmitting member 30.

In this manner, as illustrated in FIG. 6 and FIG. 7, regarding thesecond planetary gear unit PR, in third speed forward, fifth speedforward, and first speed reverse, the rotation of the input shaft 2 isinput to the sun gear S1 by engaging the clutch C3, and the reducedspeed rotation is output to the ring gear R3 through the fixed carrierCR1, to the sun gear S3 via the transmitting member 30. In this case,because the ring gear R1 and the sun gear S3 are rotating at a reducedspeed, the transmitting member 30 transmits a relatively large torque.On the other hand, in first speed forward, second speed forward, fourthspeed forward, and sixth speed forward, the rotation of the sun gear S3is input to the ring gear R1 via the transmitting member 30, andfurther, because the clutch C3 is released, as FIG. 7 illustrates, thesun gear S1 rotates based on the rotation of ring gear R1 and the fixedstate of carrier CR1.

The operations other than described above for the second planetary gearunit PR are similar to those previously described for the firstembodiment (see FIG. 2 and FIG. 3), and accordingly description thereofwill be omitted here.

As described above, in the automatic transmission 1 ₃ of this thirdembodiment, due to the second planetary gear unit PR and the clutch C1being located on one axial side of the first planetary gear unit PU, andthe clutch C2 being located on the other side of the first planetarygear unit PU, the second planetary gear unit PR and the first planetarygear unit PU can be placed more closely together, compared to the casewherein, for example, two clutches C1 and C2 are located between thesecond planetary gear unit PR and the first planetary gear unit PU, andtherefore the transmitting member 30 can be made relatively shorter. Inthis manner, the automatic transmission can be made more compact andmore lightweight. Further, because the inertia (inertial force) isreduced, the controllability of the automatic transmission is increased,and the occurrence of speed change shock can be reduced. Further,compared to the case wherein three clutches C1, C2, C3 are located onone side of the first planetary gear unit PU, the oil lines (forexample, 2 a, 2 b, 91, 92, 93) that supply the hydraulic servos 11, 12,and 13 of these clutches C1, C2, C3 can be more easily constructed, themanufacturing process can be simplified, and the costs can be reduced.

Further, due to mounting the hydraulic servos 11, 12, and 13 on theinput shaft 2, the seal rings 81 and 82 can seal the bosses 3 a and 3 bto the input shaft 2 to connect the oil lines 2 a and 2 b, 2 c providedwithin input shaft 2, to the oil chambers of hydraulic servos 11, 12,and 13 without providing the seal rings between, for example, the inputshaft 2 and the hydraulic servos 11, 12, and 13. Therefore, the oilsupply can be connected simply by providing the seal rings 81 and 82 foreach of the hydraulic servos 11, 12, and 13, sliding resistance from theseal rings can be minimized, and therefore the efficiency of theautomatic transmission can be improved.

Further, because the counter gear 5 is located between the firstplanetary gear unit PU and the second planetary gear unit PR, thecounter gear 5 can be located in approximately the axial center of theautomatic transmission. For example, enlargement towards the rear (whenthe input side facing the drive source is the “front”) is not necessarybecause the counter gear 5 is mounted to mate with the drive wheeltransmission device. Because of this, particularly in the case of an FFvehicle, the interference with the front wheels is reduced, themountability on a vehicle can be improved, and the steering angle can begreatly increased, for example.

In transmissions where the clutch C3 is placed between the ring gear R1and the sun gear S3 for example, the clutch must engage and disengagethe high torque, reduced speed rotation, and therefore must berelatively large. However, in the present invention, by placing clutchC3 between the input shaft 2 and the sun gear S1, the engaging anddisengaging of the clutch C3 controls the transfer of rotation of theinput shaft 2 to the sun gear and thereby indirectly controls output ofthe reduced speed rotation from the ring gear R1. Therefore, the clutchC3 can be made more compact, and therefore the automatic transmissioncan be made more compact.

Further, the automatic transmission 1 ₃ according to this thirdembodiment is directly coupled in fourth speed forward. Therefore, infifth speed forward and sixth speed forward, the gear ratio can be ahigh ratio, and in the event that the vehicle is running at a highspeed, the engine speed can be lower, thus allowing the vehicle to runmore quietly at a high speed.

Fourth Embodiment

The fourth embodiment, which is a partial modification of the firstembodiment, will now be described with reference to FIG. 8 through FIG.10. Components of the fourth embodiment which are the same as those ofthe first embodiment are denoted by the same reference numerals, anddescription thereof omitted, except for partially modified components.

As FIG. 8 illustrates, the automatic transmission 1 ₄ of the fourthembodiment has a brake (third brake) B3 instead of the clutch C3, andthe carrier CR1 of the second planetary gear unit PR can be fixed by thebrake B3.

The brake B3 is located on the side of the second planetary gear unit PR(right side of diagram) opposite the first planetary gear unit PU. Thisbrake B3 has a hydraulic servo 16, friction plates 76, and a hub unit33.

The hub unit 33 of this brake B3 is connected to one side plate of thecarrier CR1, and this carrier CR1 is rotatably supported by the boss 3 aor the input shaft 2. The sun gear S1 is connected to the input shaft 2and the friction plates 74 of the brake B1 are splined to the outercircumferential surface of the ring gear R1. This ring gear R1 isconnected to the sun gear S3 via transmitting member 30.

Operations of the automatic transmission 1 ₄ of the fourth embodimentwill now be described below, with reference to FIG. 8, FIG. 9, and FIG.10. As with the above-described first embodiment, the vertical axes ofthe speed line diagram illustrated in FIG. 10 indicate the speeds of thevarious rotary components, and the horizontal axis indicates thecorresponding gear ratios of these rotary components. Regarding thefirst planetary gear unit PU section of this speed line diagram, thevertical axis to the farthest right side of FIG. 10 corresponds to sungear S3, and moving to the left within the diagram, the vertical axescorrespond to the carrier CR2, the ring gear R2, and the sun gear S2.Regarding the second planetary gear unit PR section of this speed linediagram, the vertical axis to the farthest right side of FIG. 10corresponds to sun gear S1, and moving to the left within the diagram,the vertical axes correspond to the ring gear R1 and the carrier CR1.Further, the widths between these vertical axes are inverselyproportional to the number of teeth of each of the sun gears S1, S2, S3,and to the number of teeth of each of the ring gears R1, R3. Also, thedotted horizontal line in the diagram represents the rotationtransmitted by the transmitting member 30.

As FIG. 8 illustrates, the carrier CR1 is fixed to the case 3 byengagement of the brake B3, whereby the rotation of the input shaft 2 isinput to the sun gear S1, and the ring gear R1 rotates a reduced speed,based on the rotation of input shaft 2 input to the sun gear S1 and thebraking of the carrier CR1. By engaging the brake B3, the reduced speedrotation of the ring gear R1 is also input to the sun gear S3 via thetransmitting member 30.

As FIG. 9 and FIG. 10 illustrate, in the second planetary gear unit PRin third speed forward, fifth speed forward, and first speed reverse,the rotation of the input shaft 2 is input to the sun gear S1 byengagement of the brake B3 to fix the carrier CR1, and the reduced speedrotation is output to the ring gear R3 by the input of rotation to thesun gear S1 from the input shaft 2, and this reduced speed rotation isinput to the sun gear S3 via the transmitting member 30. In this case,the ring gear R1 and the sun gear S3 are rotating at reduced speed, andtherefore the transmitting member 30 transmits a relatively largetorque. On the other hand, in first speed forward, second speed forward,fourth speed forward, and sixth speed forward, the rotation of the sungear S3 is input to the ring gear R1 via the transmitting member 30, andfurther, because the brake B3 is released, as FIG. 10 illustrates, thecarrier CR1 rotates at a speed based on the speed of the ring gear R1and of the sun gear S1.

The operations of the third embodiment, other than those of theplanetary gear unit PR mentioned above, are similar to those of theabove-described first embodiment (see FIG. 2 and FIG. 3), and,accordingly, description thereof will be omitted.

In the automatic transmission 1 ₃ of the third embodiment, due to thesecond planetary gear unit PR and the clutch C1 being located on oneside of the first planetary gear unit PU, and the clutch C2 being on itsother side, the second planetary gear unit PR and the first planetarygear unit PU can be located more closely together as compared to thecase wherein, for example, two clutches C1 and C2 are located betweenthe second planetary gear unit PR and the first planetary gear unit PU,and the transmitting member 30 which transmits the reduced speedrotation can be made relatively shorter. By doing so, the automatictransmission can be made more compact and more lightweight. Further,because the inertia (inertial force) can be reduced, the controllabilityof the automatic transmission can be increased, and the occurrence ofspeed change shock can be reduced.

Further, since the hydraulic servos 11 and 12 are mounted on the inputshaft 2, the seal rings 81 and 82 form seals between the case 3 and theoil lines 2 a and 2 b provided within input shaft 2, and therefore oilcan be supplied to the oil chambers of hydraulic servos 11 and 12without providing seal rings between, for example, the input shaft 2 andthe hydraulic servos 11 and 12. Therefore, the oil supply can beconnected simply by providing seal rings (81 and 82) for each of thehydraulic servos 11 and 12, sliding resistance from the seal rings canbe minimized, and therefore the efficiency of the automatic transmissioncan be improved.

Further, because the counter gear 5 is located axially between theplanetary gear unit PU and the planetary gear unit PR, the counter gear5 can be located in approximately the axial center of the automatictransmission. Thus, enlargement towards the rear (when the side whichreceives input from the drive source is the “front”) is not necessarybecause the counter gear 5 is mounted to mate with the drive wheeltransmission device. Because of this, particularly in the case of a FFvehicle, interference with the front wheels is reduced, mountability ona vehicle is improved, and the steering angle is greatly increased, forexample.

Further, because the reduced speed rotation output to the firstplanetary gear unit PU from the second planetary gear unit PR iscontrolled by selective engagement of the brake B3, the number of parts(for example, drum-shaped members and so forth) can be reduced comparedto the case wherein, for example, a clutch C3 is provided. Further, thebrake B3 can receive oil supply directly from the case 3, and thereforethe configuration of the oil line can be simplified as compared toembodiments having a clutch C3.

The automatic transmission 1 ₄ according to this fourth embodiment isdirectly coupled in fourth speed forward. Therefore, in fifth speedforward and sixth speed forward, the gear ratio can be a high ratio, andparticularly when the vehicle is running at a high speed, the enginespeed can be lower, thus allowing the vehicle to run more quietly athigh speed.

Fifth Embodiment

The fifth embodiment, which is a partial modification of the firstembodiment, will be described below, with reference to FIG. 11 in anabbreviated manner, using the same reference numerals for componentsthat are the same as in the first embodiment.

As FIG. 11 illustrates, the automatic transmission 1 ₅ of the fifthembodiment has the configuration of the second planetary gear unit PRand the clutch C3 modified relative to that the automatic transmission 1₁ of the first embodiment (see FIG. 1), and further, a brake B3 isprovided to fix the carrier CR1 of the second planetary gear unit PR.

In this fifth embodiment, the clutch C3 is located on the firstplanetary gear unit PU side (left side of diagram) of the secondplanetary gear unit PR, and the brake B3 is on the other side of thesecond planetary gear unit PR, opposite the first planetary gear unitPU. The inner circumferential surface of a front portion of the drum 25of clutch C3 is splined to the friction plates 73, which are intermeshedwith friction plates splined to the hub unit 26. Further, the drum 25 isconnected to the input shaft 2, and the hub unit 26 is connected to thesun gear S1.

The brake B3 is on the side of the second planetary gear unit PR (rightside of diagram) opposite the first planetary gear unit PU. This brakeB3 comprises a hydraulic servo 16, friction plates 76, and a hub unit33. The friction plates 76 are splined to the outer circumferentialsurface of the hub unit 33, and the hub unit 33 is connected to one sideplate of the carrier CR1. Carrier CR1 is rotatably supported by theinput shaft 2 or the boss 3 a. The friction plates 74 of the brake B1are splined to the outer circumferential surface of the ring gear R1,and this ring gear R1 is connected to the sun gear S3 via transmittingmember 30.

The oil chamber of hydraulic servo 13 for the clutch C3 is connected toan oil line 2 c which is formed in parallel with oil line 2 a on theabove-mentioned input shaft 2, and this oil line 2 c is connected to theoil line 92 of the boss 3 a of the case 3. Further, this oil line 92 isconnected to an oil pressure control unit, not illustrated. In otherwords, because the hydraulic servos 11 and 13 are mounted on input shaft2, an oil line from the oil pressure control unit, not illustrated, isconnected to the oil chambers of the hydraulic servos 11 and 13 simplyby providing seal rings 81 between the boss 3 a and the input shaft 2.

Operations of the automatic transmission 1 ₅ of the fifth embodimentwill now be described below, with reference to FIG. 11, and, because thefifth embodiment is similar to the first embodiment, with reference tothe engagement chart and the speed line diagram for the first embodiment(see FIG. 2 and FIG. 3).

As FIG. 11 illustrates, the rotation of input shaft 2 is input to thesun gear S1 by engaging the clutch C3. Further, the carrier CR1 is fixedto the case 3 by engagement of the brake B3. Therefore, upon engagementof the clutch C3 and the brake B3, the ring gear R1 will rotate at areduced speed based on the rotation of input shaft 2 which is input tosun gear S1. In other words, by engaging the clutch C3 and the brake B3,the reduced speed rotation of the ring gear R1 is input to the sun gearS3 via the transmitting member 30.

By doing so, as FIG. 2 and FIG. 3 illustrate, regarding the secondplanetary gear unit PR, in third speed forward, fifth speed forward, andfirst speed reverse, the rotation of the input shaft 2 is input to thesun gear S1 by engaging the clutch C3, and further, the carrier CR1 isfixed by engagement of the brake B3, and therefore the reduced speedrotation is output to the ring gear R3 through the fixed carrier CR1,and from the ring gear R3 to the sun gear S3 via the transmitting member30. Because the ring gear R1 and the sun gear S3 are rotating at areduced speed, the transmitting member 30 transmits a relatively largetorque. In first speed forward, second speed forward, fourth speedforward, and sixth speed forward, the rotation of the sun gear S3 isinput to the ring gear R1 via the transmitting member 30, but becausethe clutch C3 and the brake B3 are released, the carrier CR1 and the sungear S1 freely rotate.

Operations of the fifth embodiment, other than those of the secondplanetary gear unit PR, are similar to those of the first embodiment(see FIG. 2 and FIG. 3), and accordingly description thereof will not berepeated here.

As described above, in the automatic transmission 1 ₅ of the presentinvention, due to location of the second planetary gear unit PR and theclutch C1 on one side of the first planetary gear unit PU, and theclutch C2 being located on the other side of the first planetary gearunit PU, the second planetary gear unit PR and the first planetary gearunit PU can be located more closely together, as compared to atransmission wherein, for example, two clutches C1 and C2 are locatedbetween the second planetary gear unit PR and the first planetary gearunit PU, and the transmitting member 30 can be made relatively shorter.Thus, the automatic transmission can be made compact and morelightweight. Further, because the inertia (inertial force) is reduced,the controllability of the automatic transmission is increased, and theoccurrence of speed change shock is reduced. Further, compared atransmission wherein three clutches C1, C2, C3 are located on one sideof the first planetary gear unit PU, the oil lines (for example, 2 a, 2b, 91, 92, 93) that supply the hydraulic servos 11, 12, and 13 of theseclutches C1, C2, C3 can be more easily constructed, the manufacturingprocess can be simplified and the costs can be reduced.

Further, since the hydraulic servos 11, 12, and 13 are mounted on theinput shaft 2, the seal rings 81 and 82 serve to connect oil supply fromthe case 3 to the oil lines 2 a and 2 b, 2 c provided within input shaft2, and therefore oil can be supplied to the oil chambers of hydraulicservos 11, 12, and 13 without providing the seal rings between, forexample, the input shaft 2 and the hydraulic servos 11, 12, and 13.Therefore, sliding resistance from the seal rings can be minimized, andthe efficiency of the automatic transmission can be improved.

Further, due to the counter gear 5 being located between the firstplanetary gear unit PU and the second planetary gear unit PR, thecounter gear 5 can be located in approximately the axial center of theautomatic transmission. For example, when the automatic transmission ismounted on a vehicle, enlargement towards the rear (when the input sidefacing the drive source is the “front”) is not necessary because thecounter gear 5 is mounted to mate with the drive wheel transmissiondevice. Because of this, particularly in the case of a FF vehicle,interference with the front wheels is reduced, mountability on a vehicleis improved, and the steering angle is greatly increased.

Again, where the clutch C3 is placed between the ring gear R1 and thesun gear S3, it must be sufficiently large to transmit the high torque,reduced speed rotation, but by placing the clutch C3 between the inputshaft 2 and the sun gear S1 it can indirectly control output of reducedspeed rotation from the ring gear R1 of the second planetary gear unitPR, and therefore can be made more compact, and likewise the automatictransmission can be made more compact.

Further, the automatic transmission 1 ₅ according to the fifthembodiment is directly coupled in fourth speed forward. Therefore, infifth speed forward and sixth speed forward, the gear ratio can be ahigh ratio, and particularly when the vehicle is running at a highspeed, the engine speed can be lower, thereby allowing the vehicle torun more quietly at a high speed.

Sixth Embodiment

A sixth embodiment, which is a partial modification of the firstembodiment, will now be described with reference to FIG. 12. Componentsof the sixth embodiment which are the same as those of the firstembodiment are denoted by the same reference numerals, and descriptionthereof omitted, except for those components partially modified.

As FIG. 12 illustrates, the automatic transmission 1 ₆ of the sixthembodiment has the clutch C2 located on the planetary gear unit PR sideof the planetary gear unit PU, and the clutch C1 is located on its otherside or, in other words, the sixth embodiment has the positions of theclutch C1 and the clutch C2 switched as compared to that of theautomatic transmission 1 ₁ of the first embodiment (see FIG. 1).

This automatic transmission 1 ₆ includes a multi-disc clutch C2comprising a hydraulic servo 12, friction plates 72, a clutch drum 23, ahub unit 24 linked to a sun gear S2 radially inward of the input shaft2, and a multi-disc clutch C3 comprising a hydraulic servo 13, frictionplates 73, a clutch drum 25, and a hub unit 24 linked to a sun gear S2at the outer circumference. The automatic transmission further includesa multi-disc brake B1 comprising a hydraulic servo 14 and frictionplates 74.

The drum 23 is connected to the input shaft 2, and the innercircumferential surface of a front portion is splined to the frictionplates 72 of the clutch C2 which can be engaged by the hydraulic servo12, and the friction plates 72 are intermeshed with friction platessplined to the hub unit 24. Further, this hub unit 24 is connected tothe above-mentioned carrier CR2.

At the other end of the input shaft 2 (left side of the diagram) is amulti-disc clutch C1 comprising a hydraulic servo 11, friction plates71, a clutch drum 21, and a hub unit 22 linked to a sun gear S2.

The inner circumferential surface of the front portion of this drum 21is splined to the friction plates 71 of the clutch C1 that can beengaged by operation of the hydraulic servo 11. The friction plates 71are intermeshed with friction plates splined to the hub unit 22 which isconnected to the sun gear S2.

The operations of the automatic transmission 1 ₆ of the sixth embodimentare similar to those of the first embodiment (see FIG. 2 and FIG. 3),and accordingly description thereof will be omitted here.

In the automatic transmission 1 ₆ of this sixth embodiment, due to thesecond planetary gear unit PR and the clutch C2 being located on oneside of the first planetary gear unit PU, and the clutch C1 beinglocated on the other side of the first planetary gear unit PU, thesecond planetary gear unit PR and the first planetary gear unit PU canbe located more closely together, as compared to a transmission wherein,for example, two clutches C1 and C2 are located between the secondplanetary gear unit PR and the first planetary gear unit PU, and thetransmitting member 30 can be made relatively shorter. In this manner,the automatic transmission can be made more compact and morelightweight. Further, because the inertia (inertial force) can bereduced, the controllability of the automatic transmission can beincreased, and the occurrence of speed change shock can be reduced.Further, compared to a transmission wherein three clutches C1, C2, C3are located on one side of the first planetary gear unit PU, the oillines (for example, 2 a, 2 b, 91, 92, 93) that supply the hydraulicservos 11, 12, and 13 of these clutches C1, C2, C3 can be more easilyconstructed, the manufacturing process can be simplified, and the costcan be reduced.

Further, since the hydraulic servos 11 and 12 are mounted on the inputshaft 2, one set of seal rings (81 or 82) serve to form a oil supplyconnection between the oil lines 2 a and 2 b within input shaft 2 andthe case 3, and therefore oil can be supplied to the oil chambers ofhydraulic servos 11 and 12 without providing seal rings between, forexample, the input shaft 2 and the hydraulic servos 11 and 12. Further,the hydraulic servo 13 can receive supply of oil directly from the boss3 a extended from the case 3, i.e., without passing through other parts,and therefore the oil supply can be connected by providing one set ofseal rings 80. Therefore, sliding resistance from the seal rings can beminimized, and the efficiency of the automatic transmission can beimproved.

Since the clutch C2 is located radially inward of the clutch C3, theclutch C3, which must transmit relatively large torque, low speedrotation, can be located near the outer circumference, and this clutchC3 and its hydraulic servo 13 can have an increased diameter, a largerpressure-receiving area, and a larger torque transmission capacity.Further, by giving the clutch C2 a smaller torque transmission capacitycompared to the clutch C3, the automatic transmission can be made morecompact.

As with the previously described embodiments, because the counter gear 5is located axially between the first planetary gear unit PU and thesecond planetary gear unit PR, the counter gear 5 can be located inapproximately the axial center of the automatic transmission. Forexample, when the automatic transmission is mounted on the vehicle,enlargement toward the rear (when the input side facing the drive sourceis the “front”) is unnecessary because the counter gear 5 is mounted tomate with the drive wheel transmission device. Because of this,particularly in the case of a FF vehicle, interference with the frontwheels is reduced, the mountability on a vehicle is improved, and thesteering angle is greatly increased.

Further, the clutch C1 engages at the relatively slow to medium speedsof first speed forward, second speed forward, third speed forward, andfourth speed forward, and therefore when clutch C1 is released at therelatively high speeds of fifth speed forward, sixth speed forward, orfirst speed reverse, the hub unit 22 that connects this clutch C1 andthe sun gear S2, in particular, rotates at a relatively high speed or inreverse (see FIG. 7). On the other hand, in fifth speed forward andfirst speed reverse the transmitting member 30 rotates at a reducedspeed, and in sixth speed forward the transmitting member 30 may befixed, and the difference in rotational speed between the hub unit 22and the transmitting member 30 can be great. However, because thisclutch C1 is located on the side of the first planetary gear unit PUopposite the second planetary gear unit PR, the hub unit 22 and thetransmitting member 30 can be spaced apart from one another. Comparedwith a transmission wherein these units are in contact due to amulti-axial configuration, decreased efficiency of the automatictransmission resulting from friction and so forth from the relativerotation of those units can be prevented.

Further, the automatic transmission 1 ₆ according to the sixthembodiment is directly coupled in fourth speed forward. Therefore, infifth speed forward and sixth speed forward, the gear ratio can be ahigh ratio, and particularly when the vehicle is running at a highspeed, the engine speed can be lowered, allowing the vehicle to run morequietly at a high speed.

The transmitting member which links the second planetary gear unit PRand the first planetary gear unit PU must be sufficiently rigid towithstand the reduced speed, high torque that it transmits. For example,a clutch that engages at a slow to medium speed or a clutch that engagesand disengages for transmission of reduced speed rotation must have alarge capacity, therefore a diameter appropriate for this capacitybecomes necessary. Therefore, in the event that the transmitting(linking) member passes on the radially outer side of this type ofclutch, an even larger diameter for those clutches becomes necessary,the diameter of the transmitting member is enlarged more than necessary,and the radial dimension of the automatic transmission as a wholebecomes greater. Accordingly, it is an object of this embodiment toreduce of the diameter, and thereby provide a more compact automatictransmission.

In this sixth embodiment, all clutches can be arranged so as to avoidneed for enlarging the diameter of the linking member, specifically byarranging a clutch C2 with a small capacity on the radially inward sideof the transmitting member 30.

Seventh Embodiment

The seventh embodiment is a partial modification of the sixth embodimentand will be described with reference to FIG. 13. Components of theseventh embodiment which are the same as those of the sixth embodimentare denoted by the same reference numerals, and description thereofomitted here, except for those components which are partially modified.

As FIG. 13 illustrates, the automatic transmission 1 ₇ of the seventhembodiment has a modified configuration of the second planetary gearunit PR, the clutch C2 and the clutch C3, as compared to the automatictransmission 1 ₆ of the sixth embodiment (see FIG. 12).

The clutch C2 and the clutch C3 are located on the side of the secondplanetary gear unit PR (right side of diagram) opposite the firstplanetary gear unit PU within the automatic transmission 1 ₇. The innercircumferential surface of a front portion of the drum 25 of this clutchC3 is splined to the friction plates 73, which are intermeshed withfriction plates splined to the hub unit 26. The drum 25 is connected tothe input shaft 2, and the hub unit 26 is connected to the sun gear S1of the second planetary gear unit PR. The clutch C2 comprises ahydraulic servo 12, friction plates 72, a drum 23, and a hub unit 24 andis located radially inward of the clutch C3, that is to say, clutch C2is enclosed within the hub unit 26.

On the other hand, radially outward of the second planetary gear unit PRis a multi-disc brake B1 that comprises a hydraulic servo 14 andfriction plates 74. The side plate of the carrier CR1 of this secondplanetary gear unit PR is fixed to and supported by the case 3. Further,the ring gear R1 is connected to the sun gear S3 by the transmittingmember 30, and the friction plates 74 of the brake B1 are splined to theouter circumferential surface of this transmitting member 30.

The operations of the automatic transmission 1 ₇, of this seventhembodiment are similar to those of the third embodiment (see FIG. 6 andFIG. 7), and accordingly description thereof will be omitted here.

In the automatic transmission 1 ₇ of the seventh embodiment, due to thesecond planetary gear unit PR and the clutch C2 being located on oneside of the first planetary gear unit PU, and the clutch C1 beinglocated on the other side of the first planetary gear unit PU, thesecond planetary gear unit PR and the first planetary gear unit PU canbe located more closely together, as compared to an embodiment wherein,for example, two clutches C1 and C2 are located between the secondplanetary gear unit PR and the first planetary gear unit PU, and thetransmitting member 30 which transmits the reduced speed rotation can bemade relatively shorter. In this manner, the automatic transmission canbe made more compact and more lightweight. Further, because the inertia(inertial force) can be reduced, controllability of the automatictransmission can be increased, and the occurrence of speed change shockcan be reduced. Further, compared to the case wherein three clutches C1,C2, C3 are located on one side of the first planetary gear unit PU, theoil lines (for example, 2 a, 2 b, 91, 92, 93) that supply the hydraulicservos 11, 12, and 13 of these clutches C1, C2, C3 can be more easilyconstructed, the manufacturing process can be simplified, and the costcan be reduced.

Further, since the hydraulic servos 11 and 12 are mounted on the inputshaft 2, one set of seal rings 81 and 82 serve to connect and the supplyof oil from the case 3 to the oil lines 2 a and 2 b provided withininput shaft 2, and therefore oil can be supplied to the oil chambers ofhydraulic servos 11 and 12 without providing seal rings between, forexample, the input shaft 2 and the hydraulic servos 11 and 12. Further,the hydraulic servo 13 can be supplied with oil directly from the boss 3a extended from the case 3, i.e., without passing through othercomponents, and therefore oil supply can be connected by providing oneset of seal rings 80. Therefore, sliding resistance from the seal ringscan be minimized, and efficiency of the automatic transmission can beimproved.

Further, since the counter gear 5 is located axially between the firstplanetary gear unit PU and the second planetary gear unit PR, thecounter gear 5 can be located in approximately the axial center of theautomatic transmission. In this embodiment also, enlargement toward therear (when the input side facing the drive source is the “front”) is notnecessary because the counter gear 5 is mounted to mate with the drivewheel transmission device. Because of this, particularly in the case ofa FF vehicle, interference with the front wheels is reduced,mountability on a vehicle is improved, and the steering angle is greatlyincreased.

The clutch C1 engages at the relatively slow to medium speeds of firstspeed forward, second speed forward, third speed forward, and fourthspeed forward, and therefore when this clutch C1 is released at therelatively high speeds of fifth speed forward, sixth speed forward, orfirst speed reverse, in particular the hub unit 22 that connects clutchC1 and the sun gear S2 rotates at a relatively high speed or in reverse(see FIG. 7). On the other hand, in fifth speed forward and first speedreverse the transmitting member 30 rotates at a reduced speed, and insixth speed forward the transmitting member 30 can be engaged, wherebythere can be a large difference in speed as between the hub unit 22 andthe transmitting member 30. However, because clutch C1 is located on theside of the first planetary gear unit PU opposite the second planetarygear unit PR, the hub unit 22 and the transmitting member 30 can bespaced apart from one another. In comparison with a transmissionwherein, for example, these members are in contact due to a multi-axialconfiguration, decreased efficiency of the automatic transmissionresulting from friction and so forth from the relative rotation can beprevented.

If the clutch C3 were to be placed between the ring gear R1 and the sungear S3, for example, it must engage and disengage the reduced speedrotation, and therefore must be relatively large. However, by placingthe clutch C3 between the input shaft 2 and the sun gear S1, theengaging and disengaging of the rotation of the input shaft 2 by clutchC3 indirectly controls output of the reduced rotation from the ring gearR1 of the second planetary gear unit PR, and therefore the clutch C3 andthe automatic transmission as a whole can be made more compact.

Further, the automatic transmission 1 ₇ according to the seventhembodiment is directly coupled in fourth speed forward. Therefore, infifth speed forward and sixth speed forward, the gear ratio can be ahigh ratio, and particularly when the vehicle is running at a highspeed, the engine speed can be lowered, thereby allowing the vehicle torun more quietly at a high speed.

If a clutch were to be located between the second planetary gear unit PRand the first planetary gear unit PU, for example, the length of thelinking member (transmitting member) that links the second planetarygear unit PR and the first planetary gear unit PU must be axiallyelongated, and because this transmitting member transmits the reducedspeed rotation, the thickness of the unit must be increased so as towithstand the high torque, and therefore the weight is increased.Therefore, an object of the present invention is to provide an automatictransmission wherein the distance between the speed reducing secondplanetary gear unit and the first planetary gear unit is reduced, andthe weight is thereby reduced.

In this seventh embodiment, in particular, the clutch C2 is located onthe side of the second planetary gear unit PR axially opposite the firstplanetary gear unit PU, and therefore, locating a clutch between thefirst and second planetary gear units is not necessary, and the lengthof the transmitting member 30 can be made that much shorter. Therefore,the weight of the automatic transmission as a whole can be reduced.

Eighth Embodiment

The eighth embodiment, which is a partial modification of the sixthembodiment, will be described with reference to FIG. 14. Components ofthe eighth embodiment which are the same as those of the sixthembodiment are denoted by the same reference numerals, and descriptionthereof is omitted here, except for those components which are modified.

As FIG. 14 illustrates, the automatic transmission 1 ₈ of the eighthembodiment has the configuration of the clutch C2 modified, has a brakeB3 instead of a clutch C3, and enables the carrier CR1 of secondplanetary gear unit PR to be fixed by the brake B3, which featuresdiffer from those of the automatic transmission 1 ₆ of the firstembodiment (see FIG. 12).

Within the automatic transmission 1 ₈ of the eighth embodiment, thebrake B3 is located on the side of the second planetary gear unit PRaxially opposite (right side on the diagram) the planetary gear unit PU.Brake B3 comprises a hydraulic servo 16, friction plates 76, and a hubunit 33. The clutch C2, comprises a hydraulic servo 12, friction plates72, a drum 23, and a hub unit 24, and is located radially inward of thebrake B3, i.e., within the hub unit 33. The hub unit 33 of brake B3 isconnected to one side plate of the carrier CR1, and the other (opposite)side plate of the carrier CR1 is rotatably supported by the input shaft2. Further, the sun gear S1 is connected to the input shaft 2 via thedrum 24 of the clutch C2. The friction plates 74 of the brake B1 aresplined to the outer circumferential surface of the ring gear R1, andthis ring gear R1 is connected by the transmitting member 30 to the sungear S3.

The operations of the automatic transmission 1 ₈ of the eighthembodiment are similar to those of the fourth embodiment (see FIG. 9 andFIG. 10), and accordingly description thereof will not be repeated here.

In the automatic transmission 1 ₈ of the eighth embodiment, due to thesecond planetary gear unit PR and the clutch C2 being located on oneside of the first planetary gear unit PU, and the clutch C1 beinglocated on the axially opposite side of the first planetary gear unitPU, the second planetary gear unit PR and the first planetary gear unitPU can be located more closely together, as compared to the transmissionwherein, for example, two clutches C1 and C2 are located between firstand second planetary gear units, and the transmitting member 30 can berelatively shorter. By doing so, the automatic transmission can be mademore compact and more lightweight. Further, because the inertia(inertial force) is reduced, the controllability of the automatictransmission is increased, and the occurrence of speed change shock isreduced.

Further, since the hydraulic servos 11 and 12 are mounted on the inputshaft 2, the seal rings 81 and 82 serve to connect supply of oil betweenthe oil lines 2 a and 2 b provided within input shaft 2 and the case 3,and therefore oil can be supplied to the oil chambers of hydraulicservos 11 and 12 without providing the seal rings between, for example,the input shaft 2 and the hydraulic servos 11 and 12. Therefore, slidingresistance from seal rings can be minimized, and the efficiency of theautomatic transmission can be improved.

Further, since the counter gear 5 is located axially between twoplanetary gear units, the counter gear 5 is in approximately the axialcenter of the automatic transmission. As in the previously describedembodiments, enlarging toward the rear (when the input side facing thedrive source is the “front”) is not necessary because the counter gear 5is mounted to mate with the drive wheel transmission device. Because ofthis, particularly in the case of a FF vehicle, interference with thefront wheels is reduced, mountability on the vehicle is improved, andthe steering angle is greatly increased.

Further, the clutch C1 engages at the relatively slow to medium speedsof first speed forward, second speed forward, third speed forward, andfourth speed forward, and therefore when this clutch C1 is released atthe relatively high speed levels of fifth speed forward, sixth speedforward, or first speed reverse, the hub unit 22 that connects thisclutch C1 and the sun gear S2 rotates at a relatively high speed or inreverse (see FIG. 10). On the other hand, in fifth speed forward orfirst speed reverse the transmitting member 30 rotates at reduced speed,and in sixth speed forward the transmitting member 30 may be fixed insome cases, and a difference in speed between the hub unit 22 and thetransmitting member 30 can result. However, because clutch C1 is locatedon the side of the first planetary gear unit PU axially opposite thesecond planetary gear unit PR, the hub unit 22 and the transmittingmember 30 can be spaced apart from one another. In comparison with atransmission wherein, for example, these members are in contact due to amulti-axial configuration, loss in efficiency of the automatictransmission resulting from friction and so forth from the relativerotation of those units can be prevented.

Further, because the reduced speed rotation output to the firstplanetary gear unit PU from the second planetary gear unit PR is engagedand disengaged by the brake B3, the number of parts (for exampledrum-shaped members and so forth) can be reduced as compared to anembodiment employing a clutch C3. Further, the brake B3 can receive oilsupply directly from the case 3, and therefore the configuration of theoil line can be simplified as compared to an embodiment employing aclutch C3.

Further, the automatic transmission 1 ₈ according to the eighthembodiment is directly coupled in fourth speed forward. Therefore, infifth speed forward and sixth speed forward, the gear ratio can be ahigh ratio, and particularly when the vehicle is running at a highspeed, the engine speed can be lowered, allowing the vehicle to run morequietly at a high speed.

If a clutch is located between the first and second planetary gearunits, the length of the transmitting member that links the first andsecond planetary gear units must be axially elongated and since thistransmitting member transmits the reduced speed rotation, its thicknessmust be so as to withstand a high torque, and therefore the weight isalso increased. Therefore, an object of the present invention is toprovide an automatic transmission in which the distance between thespeed reducing second planetary gear unit and the first planetary gearunit is shortened and the weight is thereby reduced.

In this eighth embodiment, in particular, the clutch C2 is disposed onthe side of the second planetary gear unit PR axially opposite the firstplanetary gear unit PU, and therefore, provision of a clutch between theplanetary gear units is not necessary, and the length of thetransmitting member 30 can be made that much shorter. Therefore, weightof the automatic transmission as a whole can be reduced.

Ninth Embodiment

The ninth embodiment, which is a partial modification of the firstembodiment, will now be described with reference to FIG. 15. Componentsof the ninth embodiment which are the same as those of the firstembodiment are denoted by the same reference numerals, and descriptionthereof omitted, except for partial modifications.

As FIG. 15 illustrates, the automatic transmission 1 ₉ of the automatictransmission of the ninth embodiment has clutch C2 located axiallybetween the planetary gear units, and has the clutch C1 and the countergear 5 on the side of the first planetary gear unit PU axially oppositethe second planetary gear unit PR. Thus, the locations of the clutch C1and the clutch C2 are reversed, and further, the positions of the secondplanetary gear unit PR, the clutch C3, and the brake B1 and the positionof the counter gear 5 are reversed as compared to the automatictransmission 1 ₁ of the first embodiment (see FIG. 1).

Within the automatic transmission 1 ₉, mounted on the input shaft 2 is amulti-disc clutch C1, which comprises a hydraulic servo 11, frictionplates 71, a clutch drum 21, and a hub unit 22 linked to a sun gear S2on the radially inner side.

The oil chamber of this hydraulic servo 11 is connected to oil line 2 awhich, in turn, is connected to the oil line 91 of the boss 3 a in theform of a sleeve surrounding one end of the input shaft 2. Oil line 91connects to the oil pressure control unit, not illustrated. In otherwords, since the above-mentioned hydraulic servo 11 is mounted on inputshaft 2, oil supply from the oil pressure control unit to the oilchamber of the hydraulic servo 11 is connected simply by providing oneset of seal rings 81 between the boss 3 a and the input shaft 2.

The input shaft 2 is connected to the drum 21 having an inner surface towhich the friction plates 71 of the clutch C1 are splined. The frictionplates 71 of this clutch C1 are intermeshed with friction plates splinedto the hub unit 22 which, in turn, is connected to the sun gear S2.

On the other side of the input shaft 2 (left side in diagram) is amulti-disc clutch C2 that has a hydraulic servo 12, friction plates 72,a clutch drum 23, and a hub unit 24 linked to a carrier CR2. On theouter circumference side is a multi-disc clutch C3 that comprises anhydraulic servo 13, friction plates 73, and a clutch drum 25. Further,located on the outer circumferential side of the clutch drum 25 is amulti-disc brake B1 that comprises a hydraulic servo 14 and frictionplates 74.

The oil chamber of hydraulic servo 12 is connected to an oil line 2 bwhich is formed on the input shaft 2, and this oil line 2 b is connectedto the oil line 93 of the boss 3 b which is formed as a sleeve aroundone end of the input shaft 2. Therefore, oil communication from the oilpressure control unit to the oil chamber of the hydraulic servo 12 isconnected simply by providing one set of seal rings 82 between the boss3 a and the input shaft 2.

Further, the oil chamber of the hydraulic servo 13 is connected to anoil line 94 in the boss 3 b, which oil line 94 is connected to the oilpressure control unit, by providing one set of seal rings 84 to form aseal between the boss 3 b and the clutch drum 25.

The input shaft 2 is connected to the clutch drum 23 at the left side ofthe diagram, and the inner circumferential surface this clutch drum 23is splined to the friction plates 72 of the clutch C2 which areintermeshed with friction plates splined to the hub unit 24 which isconnected to the above-mentioned carrier CR2.

The above-mentioned clutch drum 25 is rotatably supported by the boss 3b, and a front portion of the outer circumferential surface of clutchdrum 25 is splined to friction plates 74 of the brake B1 which isengaged/disengaged by operation of the hydraulic servo 14. The innercircumferential surface of the front portion of clutch drum 25 issplined to the friction plates 73 of the clutch C3 which isengaged/disengaged by operation of the hydraulic servo 13 for the clutchC3. The friction plates 73 of this clutch C3 are intermeshed withfriction plates splined to the ring gear R1.

Further, carrier CR1 has a pinion Pa and a pinion Pb. Pinion Pb mesheswith the ring gear R1 and pinion Pa meshes with the sun gear S1 which isconnected to the input shaft 2. This carrier CR1 is secured to the boss3 b via a side plate, and this ring gear R1 is rotatably supported by asupport element 26 extending to the boss 3 b.

Further, the clutch drum 25 is connected by a linking member 30 thattransmits rotation of the ring gear R1, when the clutch C3 is engaged,to the sun gear S3 of the above-mentioned first planetary gear unit PU.

The operations of the automatic transmission 1 ₉ of this ninthembodiment are similar to those of the first embodiment (see FIG. 2 andFIG. 3), and accordingly description thereof will not be repeated here.

As described above, in the automatic transmission 1 ₉ of the ninthembodiment, because the second planetary gear unit PR and the clutch C2are located on one side of the first planetary gear unit PU, and theclutch C1 is located on the axially opposite side of the first planetarygear unit PU, the second planetary gear unit PR and the first planetarygear unit PU can be located more closely together, as compared to anautomatic transmission wherein, for example, two clutches C1 and C2 arelocated between the planetary gear units PR and PU, and the transmittingmember 30 for transmitting the reduced speed rotation can be maderelatively shorter. In this manner, the automatic transmission can bemade more compact and more lightweight. Further, because the inertia(inertial force) can be reduced, the controllability of the automatictransmission can be increased, and the occurrence of speed change shockcan be reduced. Further, compared to the case wherein three clutches C1,C2, C3 are located on one side of the planetary gear unit PU, the oillines (for example, 2 a, 2 b, 91, 93, 94) that supply the hydraulicservos 11, 12, and 13 of these clutches C1, C2, C3 can be more easilyconstructed, the manufacturing process can be simplified and the costscan be reduced.

Further, since the hydraulic servos 11 and 12 are located on the inputshaft 2, one set of seal rings 81 and 82 form an oil supply connectionby providing a seal between the case 3 and oil lines 2 a and 2 bprovided within input shaft 2. Therefore, oil can be supplied to the oilchambers of hydraulic servos 11 and 12 without providing seal ringsbetween, for example, the input shaft 2 and the hydraulic servos 11 and12. Further, the hydraulic servo 13 can receive oil directly from theboss 3 a which extends from the case 3, i.e., without passing throughother components, and therefore can be supplied oil by providing one setof seal rings 80. Therefore, the oil supply can be connected simply byproviding one set of seal rings 81 and 82, 84 for each of the hydraulicservos 11, 12, and 13, sliding resistance from the seal rings can beminimized, and therefore the efficiency of the automatic transmissioncan be improved.

Further, because the clutch C2 is located radially inward of the clutchC3, the clutch C3, which must bear a relatively large torque intransmitting the reduced speed rotation, can be located at the outercircumference, and therefore this clutch C3 and the hydraulic servo 13thereof can have an increased diameter. In particular thepressure-receiving area of the oil chamber of the hydraulic servo 13 canbe enlarged, and the torque transmitting capacity of this clutch C3 canbe increased. By designing the clutch C2 to have a smaller torquetransmitting capacity than the clutch C3, the automatic transmission canbe made more compact.

Further, the clutch C1 engages at the relatively slow to medium speedsof first speed forward, second speed forward, third speed forward, andfourth speed forward, and therefore when this clutch C1 is released atthe relatively high speed levels of fifth speed forward, sixth speedforward, or first speed reverse, the hub unit 22 that connects clutch C1to the sun gear S2 rotates at a relatively high speed or revolves inreverse (see FIG. 3). On the other hand, in fifth speed forward andfirst speed reverse the transmitting member 30 rotates at reduced speed,and in sixth speed forward the transmitting member 30 may be fixed insome cases, and therefore the speed of the hub unit 22 may differ fromthat of the transmitting member 30. However, because this clutch C1 islocated on the side of the first planetary gear unit PU axially oppositethe second planetary gear unit PR, the hub unit 22 and the transmittingmember 30 can be spaced apart from one another. In comparison to atransmission wherein, for example, these members are in contact due to amulti-axial configuration, a decrease in efficiency of the automatictransmission resulting from friction and so forth from the relativerotation of those units can be prevented.

Further, the automatic transmission 1 ₉ of the ninth embodiment isdirectly coupled in fourth speed forward. Therefore, in fifth speedforward and sixth speed forward, the gear ratio can be a high ratio, andparticularly when the vehicle is running at a high speed, the enginespeed can be lowered, thus allowing the vehicle to run more quietly at ahigh speed.

The transmitting member which connects the second planetary gear unit PRand the first planetary gear unit PU requires rigidity to withstand thereduced speed torque it transmits. For example, a clutch that engages ata slow to medium speed and a clutch that engages and disengages at areduced speed on the inner circumference side of the linking member musthave a large capacity and, therefore, must have a diameter correspondingto this capacity. Therefore, in the event that the transmitting memberpasses radially outward of this type of clutch, a diameter even largerthan the aforementioned necessary diameter is required and the automatictransmission as a whole will have a larger diameter. Therefore an objectof the present embodiment is to reduce the diameter and to provide amore compact automatic transmission.

According to the present embodiment, enlargement of the diameter of thetransmitting member is avoided by mounting a clutch C2 with a smallcapacity on the radially inward side of the transmitting member 30.

Tenth Embodiment

A tenth embodiment which is a partial modification of the ninthembodiment will now be described with reference to FIG. 16. Componentsof the tenth embodiment which are the same as those of the ninthembodiment are denoted by the same reference numerals, and descriptionthereof will be omitted here, except for the partial modifications.

As FIG. 16 illustrates, the automatic transmission 1 ₁₀ of the tenthembodiment has the configuration of the second planetary gear unit PRand that of the clutch C3 modified as compared to that of the automatictransmission of the first embodiment (see FIG. 15).

The clutch C3 is located on the side of the second planetary gear unitPR (left side of diagram) opposite the first planetary gear unit PU. Theinner circumferential surface of a front portion of the drum 25 of thisclutch C3 is splined to the friction plates 73 which are intermeshedwith friction plates splined to the hub unit 26. The drum 25 isconnected to the input shaft 2, and the hub unit 26 is connected to thesun gear S1. Further, the clutch C2, comprising a hydraulic servo 12,friction plates 72, a drum 23, and a hub unit 24, is located radiallyinward of the clutch C3, that is to say, is located within the hub unit26.

On the outer circumference side of the first planetary gear unit PU islocated a multi-disc brake B1 that comprises a hydraulic servo 14 andfriction plates 74. The side plate of the carrier CR1 of this secondplanetary gear unit PR is fixed to and supported by the case 3. Further,the ring gear R1 is connected to the transmitting member 30, and thefriction plates 74 of the brake B1 are splined to the outercircumferential surface of this transmitting member 30 which isconnected to the sun gear S3.

The operations of the automatic transmission 1 ₁₀, are similar to thoseof the third embodiment (see FIG. 6 and FIG. 7) and, accordingly,description thereof will not be repeated here.

As described above, according to the automatic transmission 1 ₁₀ of thetenth embodiment, due to the second planetary gear unit PR and theclutch C2 being located on one side of the planetary gear unit PU, andthe clutch C1 being located on the axially opposite side of the firstplanetary gear unit PU, the planetary gear units PR and PU can bepositioned more closely together, as compared to the case wherein forexample two clutches C1 and C2 are located in between the secondplanetary gear unit PR and the first planetary gear unit PU, and thetransmitting member 30 which transmits the reduced speed rotation can bemade relatively shorter. In this manner, the automatic transmission canbe made more compact and more lightweight. Further, because the inertia(inertial force) can be reduced, the controllability of the automatictransmission can be increased, and the occurrence of speed change shockcan be reduced. Further, compared to the case wherein three clutches C1,C2, C3 are located on one side of the planetary gear unit PU, the oillines (for example, 2 a, 2 b, 91, 93, 94) that supply the hydraulicservos 11, 12, and 13 of these clutches C1, C2, C3 can be more easilyconstructed, the manufacturing process can be simplified and the costscan be reduced.

Further, since the hydraulic servos 11 and 12 are located on the inputshaft 2, one set of seal rings 81 and 82 seal the case 3 and connectsupply of oil to the oil lines 2 a and 2 b provided within input shaft2, and therefore oil can be supplied to the oil chambers of thehydraulic servos 11 and 12 without providing seal rings between, forexample, the input shaft 2 and the hydraulic servos 11 and 12. Further,the hydraulic servo 13 can receive supply of oil directly from the boss3 b which extends from the case 3, without passing through othercomponents, and therefore the oil supply can be connected by providingone set of seal rings 84. Therefore, oil can be supplied simply byproviding one set of seal rings 81 and 82, 84 each for the hydraulicservos 11, 12, and 13, sliding resistance from the seal rings can beminimized, and therefore the efficiency of the automatic transmissioncan be improved.

Further, the clutch C1 engages in the relatively slow to medium speedsof first speed forward, second speed forward, third speed forward, andfourth speed forward, and therefore when this clutch C1 is released atthe relatively high speeds of fifth speed forward, sixth speed forward,or first speed reverse, in particular the hub unit 22 that connects thisclutch C1 and the sun gear S2 rotates at a relatively high speed or inreverse (see FIG. 7). On the other hand, in fifth speed forward or firstspeed reverse the transmitting member 30 rotates at the reduced speed,and in sixth speed forward the transmitting member 30 may be fixed insome cases, and a difference in speed as between the hub unit 22 and thetransmitting member 30 can occur. However, because this clutch C1 islocated on the side of the first planetary gear unit PR axially oppositethe second planetary gear unit PR, the hub unit 22 and the transmittingmember 30 can be spaced apart from one another. In comparison with thecase wherein, for example, these members are in contact due to amulti-axial configuration, a decrease in efficiency of the automatictransmission resulting from friction and so forth from the relativerotation of those units can be prevented.

If the clutch C3 is placed between the ring gear R1 and the sun gear S3,for example, the reduced speed rotation must be engaged and disengaged,and consequently the clutch C3 must be relatively large, but by placingclutch C3 between the input shaft 2 and the sun gear S1, the engagingand disengaging of the rotation of the input shaft 2 by this clutch C3indirectly causes the reduced speed rotation output from the ring gearR1 of the second planetary gear unit PR to be engaged and disengaged,and the clutch C3 can be made more compact, and therefore the automatictransmission can be made more compact.

Further, the automatic transmission 1 ₁₀ of this tenth embodiment isdirectly coupled in fourth speed forward. Therefore, in fifth speedforward and sixth speed forward, the gear ratio can be a high ratio, andparticularly when the vehicle is running at a high speed, the enginespeed can be lowered, thus allowing the vehicle to run more quietly at ahigh speed.

When a clutch is located between the second planetary gear unit PR andthe first planetary gear unit PU for example, the length of thetransmitting member that links the second planetary gear unit PR withthe first planetary gear unit PU is axially elongated, and since ittransmits the reduced speed rotation, the thickness of the member mustbe increased so as to withstand the torque, and therefore its weight isalso increased. Therefore an object of the present invention is toprovide an automatic transmission that can shorten the distance betweenthe speed reducing second planetary gear unit and the first planetarygear unit, and thereby reduce the weight.

With the tenth embodiment, in particular, the clutch C2 is disposed onthe side of the second planetary gear unit PR axially opposite the firstplanetary gear unit PU, and, therefore, provision of a clutch betweenthe second planetary gear unit PR and the first planetary gear unit PUis not necessary, and the length of the transmitting member 30 can bemade that much shorter. Therefore, weight of the automatic transmissionas a whole can be reduced.

Eleventh Embodiment

The eleventh embodiment is a partial modification of the ninthembodiment and will be described with reference to FIG. 17. Componentsof the eleventh embodiment which are the same as those of the ninthembodiment are denoted by the same reference numerals, and descriptionthereof will be omitted, except for the partial modifications.

As FIG. 17 illustrates, the automatic transmission 1 ₁₁ of the eleventhembodiment has a modified configuration of the clutch C2, and further,has a brake B3 instead of a clutch C3, and thereby enables the carrierCR1 of the second planetary gear unit PR to be fixed by the brake B3, inwhich respects it differs from the automatic transmission 1 ₉ of theninth embodiment (see FIG. 15).

Within the automatic transmission 1 ₁₁, the brake B3 is located on theside of the second planetary gear unit PR opposite the first planetarygear unit PU (left side of the diagram). This brake B3 comprises ahydraulic servo 16, friction plates 76, and a hub unit 33. Further, theclutch C2, comprising a hydraulic servo 12, friction plates 72, drum 23,and a hub unit 24, is located on the radially inward side of the brakeB3, that is to say, it is positioned within the hub unit 33. The hubunit 33 of this brake B3 is connected to one side plate of the carrierCR1, and the other side plate of this carrier CR1 is rotatably supportedby the input shaft 2. Further, the sun gear S1 is connected to the inputshaft 2 via the drum 23 of the clutch C2. Also, the friction plates 74of the brake B1 are intermeshed with friction plates splined to theouter circumferential surface of the ring gear R1, and this ring gear R1is connected to the sun gear S3 via this transmitting member 30.

The operations of the automatic transmission 1 ₁₁, of this eleventhembodiment are similar to those of the fourth embodiment (see FIG. 9 andFIG. 10), and accordingly description thereof will not be repeated here.

As described above, in the automatic transmission 1 ₁₁ of the eleventhembodiment, due to the second planetary gear unit PR and the clutch C2being located on one side of the first planetary gear unit PU, and theclutch C1 being located on the axially opposite side of the firstplanetary gear unit PU, the planetary gear units PR and PU can belocated more closely together, as compared to the case wherein, forexample, two clutches C1 and C2 are located between the planetary gearunits PR and PU, and the transmitting member 30 for transmitting reducedspeed rotation can be made relatively shorter. By doing so, theautomatic transmission can be made more compact and more lightweight.Further, because the inertia (inertial force) can be reduced, thecontrollability of the automatic transmission can be increased, and theoccurrence of speed change shock can be reduced.

Further, since the hydraulic servos 11 and 12 are provided on the inputshaft 2, the seal rings 81 and 82 seal the case 3 to the oil lines 2 aand 2 b provided within input shaft 2, and therefore oil can be suppliedto the oil chambers of hydraulic servos 11 and 12 without providing theseal rings between, for example, the input shaft 2 and the hydraulicservos 11 and 12. Therefore, oil can be supplied simply by providing theseal rings 81 and 82 for each of the hydraulic servos 11 and 12, slidingresistance from the seal rings can be minimized, and therefore theefficiency of the automatic transmission can be improved.

Because the clutch C1 engages at the relatively slow to medium speeds offirst speed forward, second speed forward, third speed forward, andfourth speed forward, when this clutch C1 is released at the relativelyhigh speeds of fifth speed forward, sixth speed forward, or first speedreverse, the hub unit 22 in particular, that connects this clutch C1 andthe sun gear S2, rotates at a relatively high speed or in reverse (seeFIG. 10). On the other hand, in fifth speed forward or first speedreverse the transmitting member 30 rotates at the reduced speed, and insixth speed forward the transmitting member 30 may be fixed in somecases, and therefore there will be a difference in speeds between thehub unit 22 and the transmitting member 30. However, because this clutchC1 is located axially opposite the second planetary gear unit PRrelative to the first planetary gear unit PU, the hub unit 22 and thetransmitting member 30 can be spaced apart from one another. Incomparison with the case wherein, for example, these members are incontact due to a multi-axial configuration, a loss in efficiency of theautomatic transmission resulting from friction and so forth from therelative rotation of those units can be prevented.

Further, since the reduced speed rotation output to the first planetarygear unit PU from the second planetary gear unit PR is controlled by thebrake B3, the number of parts (for example drum-shaped members and soforth) can be reduced as compared to a case wherein, for example, aclutch C3 is provided. Further, the brake B3 can connect directly withan oil line in the case 3, and therefore the configuration of the oilline can be simplified as compared to the case wherein, for example, aclutch C3 is provided.

Further, the automatic transmission 1 ₁₁ according to this eleventhembodiment is directly coupled in fourth speed forward. Therefore, fifthspeed forward and sixth speed forward, the gear ratio can be a highratio, and particularly when the vehicle is running at a high speed, theengine speed can be lowered, and this allows the vehicle to run morequietly at a high speed.

When a clutch is located between the second planetary gear unit PR andthe first planetary gear unit PU for example, the length of thetransmitting member that links the planetary gear units PR and PU mustbe axially elongated, and since this transmitting member transmitsreduced speed rotation, its thickness must be increased so as towithstand this load, and therefore its weight is also increased.Therefore an object of the present invention is to provide an automatictransmission that can shorten the distance between the speed reducingsecond planetary gear unit and the first planetary gear unit, and reducethe weight.

With this eleventh embodiment, in particular, the clutch C2 is disposedaxially opposite the first planetary gear unit PU relative to the secondplanetary gear unit PR, and therefore, providing a clutch between theplanetary gear units PR and PU is not necessary, and the length of thetransmitting member 30 can be made that much shorter. Therefore, weightof the automatic transmission as a whole can be reduced.

Twelfth Embodiment

A twelfth embodiment, which is a partial modification of the firstembodiment, will now be described, with reference to FIG. 18. Componentsof the twelfth embodiment which are the same as those of the firstembodiment will be denoted by the same reference numerals, anddescription thereof omitted, except for partial modifications.

As FIG. 18 illustrates, the automatic transmission 1 ₁₂ of the automatictransmission of the twelfth embodiment has the second planetary gearunit PR, the clutch C3, and the brake B1 located axially opposite thecounter gear 5 relative to the first planetary gear unit PU (left sidein the drawing), and in this respect differs from the automatictransmission 1 ₁ of the first embodiment (see FIG. 1).

Within the automatic transmission 1 ₁₂, on input shaft 2 is mounted amulti-disc clutch C2, which comprises a hydraulic servo 12, frictionplates 72, a clutch drum 23, and a hub unit 24 linked to the sun gear S2on the radially inner side.

The oil chamber of this hydraulic servo 12 is connected to an oil line 2a which is formed on the above-mentioned input shaft 2, and this oilline 2 a is connected to the oil line 91 in the boss unit 3 a. Further,this oil line 91 is connected to an oil pressure control unit, notillustrated. Thus, because the hydraulic servo 12 is mounted on inputshaft 2, oil pressure communication between the oil pressure controlunit and the oil chamber of the hydraulic servo 12 is provided by oneset of seal rings 81 which form a seal between the boss 3 a and theinput shaft 2.

The input shaft 2 is connected to the clutch drum 23 which has its innercircumferential surface splined to the friction plates 72 of the clutchC2 which is operated by the hydraulic servo 12. The friction plates 72of this clutch C2 are intermeshed with friction plates splined to thehub unit 24 which is connected to the carrier CR2.

At the other end of the input shaft 2 (left end in diagram) is amulti-disc clutch C1 operated by a hydraulic servo 11 and includingfriction plates 71, a clutch drum 21, and a hub unit 22 linked to a sungear S2. Adjacent the outer circumference is a multi-disc clutch C3operated by a hydraulic servo 13, and including friction plates 73, anda clutch drum 25. Further, radially outward of the clutch drum 25 is amulti-disc brake B1 that comprises a hydraulic servo 14 and frictionplates 74.

The oil chamber of this hydraulic servo 11 is connected to an oil line 2b which is formed in the above-mentioned input shaft 2, and this oilline 2 b is provided along the edge of the case 3 that is opposite theabove-mentioned boss unit 3 a, and is connected to the oil line 93 ofthe boss 3 b which is formed as a sleeve around one end of the inputshaft 2. Therefore, oil pressure communication between the oil pressurecontrol unit and the oil chamber of the hydraulic servo 11 is providedby one set of seal rings 82 which form a seal between the boss unit 3 band the input shaft 2.

The oil chamber of the hydraulic servo 13 is connected to an oil line 94in the boss 3 b which also is connected to the oil pressure controlunit. Thus, for the hydraulic servo 13, oil communication between theoil pressure control unit and the oil chamber of the hydraulic servo 13is established by one set of seal rings 84 which provide a seal betweenthe boss 3 b and the clutch drum 25.

Further, the input shaft 2 is connected to the clutch drum 21 on theleft side of the diagram, and located radially outward of this clutchdrum 21 are the friction plates 71 of the clutch C1 which is operated bythe hydraulic servo 11. Friction plates 71 are splined to the clutchdrum 21 and are intermeshed with friction plates splined to the hub unit22 which is connected to the sun gear S2.

The clutch drum 25 is rotatably supported by the boss 3 b and its outercircumferential surface, at a front portion thereof, is splined to thefriction plates 74 of the brake B1 which is operated by the hydraulicservo 14. The inner circumferential surface of the front portion of thisclutch drum 25 is splined to the friction plates 73 of the clutch C3which is operated by the hydraulic servo 13. The friction plates 73 ofthis clutch C3 are intermeshed with friction plates splined to the ringgear R1.

The carrier CR1 supports a pinion Pb, which meshes with the ring gearR1, and a pinion Pa which meshes with the sun gear S1 which, in turn, isconnected to the input shaft 2. The carrier CR1 is secured to the boss 3b via a side plate, and ring gear R1 is rotatably supported by asupporting element 26 extending from the boss 3 b.

Further, the clutch drum 25 is connected to one end of a transmittingmember 30 that transmits the rotation of the ring gear R1 when theclutch C3 is engaged. The opposite end of this transmitting member 30 isconnected to the sun gear S3 of the first planetary gear unit PU.

The operations of the automatic transmission 1 ₁₂, of this twelfthembodiment are similar to those of the first embodiment (see FIG. 2 andFIG. 3), and accordingly description thereof will not be repeated here.

As described above, according to the automatic transmission 1 ₁₂ of thetwelfth embodiment, because the second planetary gear unit PR and theclutch C1 located on one side of the planetary gear unit PU, and theclutch C2 is located on the axially opposite side of the planetary gearunit PU, the planetary gear units PR and PU can be located more closelytogether, as compared to the case wherein, for example, two clutches C1and C2 are located between the planetary gear units PR and PU, and thetransmitting member 30 for transmitting the reduced speed rotation canbe made relatively shorter and the automatic transmission can be mademore compact and lightweight. Further, because the inertia (inertialforce) can be reduced, the controllability of the automatic transmissioncan be increased, and the occurrence of speed change shock can bereduced. Further, compared to the case wherein three clutches C1, C2, C3are located on one side of the planetary gear unit PU, the oil lines(for example, 2 a, 2 b, 91, 93, 94) that supply the hydraulic servos 11,12, and 13 can be constructed more easily, the manufacturing process canbe simplified, and the costs can be reduced.

Further, since the hydraulic servos 11 and 12 are mounted on the inputshaft 2, one set of seal rings 81 and 82 provide a seal between the case3 and oil lines 2 a and 2 b provided within input shaft 2, and thereforeoil can be supplied to the oil chambers of hydraulic servos 11 and 12without providing seal rings between, for example, the input shaft 2 andthe hydraulic servos 11 and 12. Further, the hydraulic servo 13 canreceive a supply of oil directly from the boss 3 a which extends fromthe case 3, i.e. without passing through other components, by provisionof one set of seal rings 80. Therefore, oil supply can be secured simplyby providing one set of seal rings 81 and 82, 84 for each of thehydraulic servos 11, 12, and 13, sliding resistance from the seal ringscan be minimized, and therefore the efficiency of the automatictransmission can be improved.

Further, due to the clutch C3 being arranged radially outward of theclutch C1, the clutch C3, which must transmit a relatively large torquewith transmission of the reduced speed rotation and its hydraulic servo13 can have an increased diameter, the pressure-receiving area of theoil chamber of the hydraulic servo 13 can be enlarged, and the torquetransmission capacity of clutch C3 can be increased. Further, byproviding the clutch C1 with a smaller torque transmission capacity ascompared to that of the clutch C3, the automatic transmission can bemade more compact.

Further, because the automatic transmission 1 ₁₂ of the twelfthembodiment is directly coupled in fourth speed forward, in fifth speedforward and in sixth speed forward, the gear ratio can be a high ratio,and particularly when the vehicle is running at a high speed, the enginespeed can be lowered, thus allowing the vehicle to run more quietly at ahigh speed.

Thirteenth Embodiment

A thirteenth embodiment, which is a partial modification of the twelfthembodiment, will now be described with reference to FIG. 19. Componentsof the thirteenth embodiment which are the same as those of the twelfthembodiment are denoted by the same reference numerals, and descriptionthereof omitted, except for the partial modifications.

As FIG. 19 illustrates, the automatic transmission 1 ₁₃ of thethirteenth embodiment has the configuration of the second planetary gearunit PR, the clutch C1, and the clutch C3 modified relative to thetwelfth embodiment (see FIG. 18).

In this thirteenth embodiment, the clutches C1 and C3 are located on theside of the second planetary gear unit PR (left side of diagram)opposite the first planetary gear unit PU. The inner surface of a frontportion of the drum 25 of this clutch C3 is splined to the frictionplates 73 which are intermeshed with friction plates splined to the hubunit 26. The clutch drum 25 is connected to the input shaft 2, and thehub unit 26 is connected to the sun gear S1. Further, the clutch C1comprising a hydraulic servo 12, friction plates 71, a clutch drum 21,and a hub unit 22 is located radially inward of the clutch C3, that isto say, is enclosed within the hub unit 26.

Radially outward of the second planetary gear unit PR is a multi-discbrake B1 that comprises a hydraulic servo 14 and friction plates 74. Theside plate of the carrier CR1 of the second planetary gear unit PR isfixed to and supported by the case 3. Further, the ring gear R1 isconnected to the transmitting member 30, and the friction plates 74 ofthe brake B1 are splined to the outer circumferential surface oftransmitting member 30, which, in turn, is connected to the sun gear S3.

The operations of the automatic transmission 1 ₁₃ are similar to thoseof the third embodiment (see FIG. 6 and FIG. 7) and accordinglydescription thereof will not be repeated here.

As described above, in the automatic transmission 1 ₁₃ of the thirteenthembodiment, because the second planetary gear unit PR and the clutch C1are located on one side of the planetary gear unit PU, and the clutch C2is located on the axially opposite side of the first planetary gear unitPU, the planetary gear units PR and PU can be located more closelytogether, as compared to a transmission wherein, for example, twoclutches C1 and C2 are located between the planetary gear units PR andPU, and the transmitting member 30 for transmitting reduced speedrotation can be made relatively shorter. By doing so, the automatictransmission can be made more compact and more lightweight. Further,because the inertia (inertial force) can be reduced, the controllabilityof the automatic transmission can be increased, and the occurrence ofspeed change shock can be reduced. Further, compared to the case whereinthree clutches C1, C2, C3 are located on one side of the first planetarygear unit PU, the oil lines (for example, 2 a, 2 b, 91, 93, 94) thatsupply the hydraulic servos 11, 12, and 13 of these clutches C1, C2, C3can be more easily constructed, the manufacturing process can besimplified, and the costs can be reduced.

Further, since the hydraulic servos 11 and 12 are mounted on the inputshaft 2, one set of seal rings 81 and 82 serve to seal the case 3 to theinput shaft 2 and thereby connect a supply of oil to the oil lines 2 aand 2 b provided within input shaft 2. Thus, oil can be supplied to theoil chambers of hydraulic servos 11 and 12 without providing seal ringsbetween, for example, the input shaft 2 and the hydraulic servos 11 and12. Further, the hydraulic servo 13 can be supplied with oil from theboss 3 b extended from the case 3, without passing through other parts,by providing one set of seal rings 84. Because oil can be supplied byproviding one set of seal rings 81 and 82, 84 for each of the hydraulicservos 11, 12, and 13, sliding resistance from the seal rings can beminimized, and therefore the efficiency of the automatic transmissioncan be improved.

Further, because the clutch C1 is located radially inward of the clutchC3, the clutch C3, which must transmit a relatively large torque inorder to transmit the reduced speed rotation, can be located on theouter circumference side, and therefore clutch C3 and the hydraulicservo 13 thereof can have an increased diameter. In particular, thepressure-receiving area of the oil chamber of the hydraulic servo 13 canbe enlarged, and the torque transmission capacity of clutch C3 can beincreased. Further, by designing the clutch C1 to have a smaller torquetransmission capacity as compared to the clutch C3, the automatictransmission can be made more compact.

In contrast, for example, if the clutch C3 were to be placed between thering gear R1 and the sun gear S3, it would engage and disengage thereduced speed, high torque rotation, and would need to be relativelylarge. However, by locating clutch C3 between the input shaft 2 and thesun gear S1, engagement and disengagement of this clutch C3 indirectlycauses the reduced speed rotation output from the ring gear R1 of thesecond planetary gear unit PR to be engaged and disengaged, andtherefore the clutch C3 can be made more compact and the automatictransmission as a whole can be made more compact.

Further, the automatic transmission 1 ₁₃ of the thirteenth embodiment isdirectly coupled in fourth speed forward. Therefore, at fifth speedforward and sixth speed forward, the gear ratio can be a high ratio and,particularly when the vehicle is running at a high speed, the enginespeed can be lowered, thus allowing the vehicle to run more quietly at ahigh speed.

If a clutch is located between the planetary gear units PR and PU, thelength of the transmitting member that links the planetary gear units PRand PU must be axially elongated, and since this transmitting memberreceives the reduced speed rotation, the thickness of the member must beincreased so as to withstand the high torque, and therefore the weightis also increased. Therefore an object of the present invention is toprovide an automatic transmission that can shorten the distance betweenthe planetary gear units, and thereby prevent increase in weight.

In this thirteenth embodiment, because the clutch C1 is disposed on theside of the planetary gear unit PR axially opposite the planetary gearunit PU, provision of a clutch between the planetary gear units PR andPU is not necessary, and the transmitting member 30 can be made thatmuch shorter. Therefore, an increase in weight of the automatictransmission as a whole can be avoided.

Fourteenth Embodiment

A fourteenth embodiment, which is a partial modification of the twelfthembodiment, will now be described with reference to FIG. 20. Componentsof the fourteenth embodiment which are the same as those of the twelfthembodiment are denoted by the same reference numerals, and descriptionthereof omitted, except for partial modifications.

As FIG. 20 illustrates, the automatic transmission 1 ₁₄ of thefourteenth embodiment differs from that of the twelfth embodiment in theconfiguration of the clutch C2, in having a brake B3 instead of a clutchC3, and in enabling the carrier CR1 of the second planetary gear unit PRto be fixed by the brake B3.

Within the automatic transmission 1 ₁₄, the brake B3 is located on theside of the planetary gear unit PR axially opposite (left side on thediagram) the planetary gear unit PU. This brake B3 comprises a hydraulicservo 16, friction plates 76, and a hub unit 33. The clutch C1 comprisesa hydraulic servo 11, friction plates 71, a clutch drum 21, and a hubunit 22, and is located radially inward of the brake B3, enclosed withinthe hub unit 33. The hub unit 33 of this brake B3 is connected to oneside plate of the carrier CR1, and the other side plate of the carrierCR1 is rotatably supported by the input shaft 2. Further, the sun gearS1 is connected to the input shaft 2 via the drum 21 of the clutch C1.The friction plates 74 of the brake B1 are intermeshed with frictionplates splined to the outer circumferential surface of the ring gear R1,and this ring gear R1 is connected to the sun gear S3 by transmittingmember 30.

The operations of the automatic transmission 1 ₁₄ of this fourteenthembodiment are similar to those of the fourth embodiment (see FIG. 9 andFIG. 10), and accordingly description thereof will not be repeated here.

In the automatic transmission 1 ₁₄ of the fourteenth embodiment, due tothe second planetary gear unit PR and the clutch C1 being located on oneside of the planetary gear unit PU, and the clutch C2 being located onthe axially opposite side of the planetary gear unit PU, the planetarygear units PR and PU can be located more closely together as comparedto, for example, a transmission wherein two clutches C1 and C2 arelocated between the planetary gear units PR and PU, and the transmittingmember 30 for transmitting reduced speed rotation can be made relativelyshorter. In this manner, the automatic transmission can be made morecompact and more lightweight. Further, because the inertia (inertialforce) can be reduced, the controllability of the automatic transmissioncan be increased, and the occurrence of speed change shock can bereduced. Further, compared to a transmission wherein three clutches C1,C2, C3 are located on one side of the planetary gear unit PU, the oillines (for example, 2 a, 2 b, 91, 93) that supply oil to the hydraulicservos 11 and 12 of these clutches C1 and C2, can be more easilyconstructed, the manufacturing process can be simplified and the costscan be reduced.

Further, since the hydraulic servos 11 and 12 are provided on the inputshaft 2, the seal rings 81 and 82 seal the case 3 to the oil lines 2 aand 2 b provided within input shaft 2, and therefore oil can be suppliedto the oil chambers of hydraulic servos 11 and 12 without providing sealrings between, for example, the input shaft 2 and the hydraulic servos11 and 12. Therefore, the oil supply can be connected simply byproviding the seal rings 81 and 82 for each of the hydraulic servos 11and 12, sliding resistance from the seal rings can be minimized, andtherefore the efficiency of the automatic transmission can be improved.

Further, since output of the reduced speed rotation to the firstplanetary gear unit PU from the second planetary gear unit PR iscontrolled by the brake B3, the number of parts (for example drummembers and so forth) can be reduced as compared to embodiments having aclutch C3. Further, the brake B3 can connect directly to an oil line inthe case 3, and therefore the configuration of the oil line can besimplified as compared to the embodiments including a clutch C3.

Further, the automatic transmission 1 ₁₄ of the fourteenth embodiment isdirectly coupled in fourth speed forward. Therefore, in fifth speedforward and sixth speed forward, the gear ratio can be a high ratio, andparticularly when the vehicle is running at a high speed, the enginespeed can be lowered, thereby allowing the vehicle to run more quietlyat high speed.

If a clutch is located between the planetary gear units PR and PU, thelength of the transmitting member that links the planetary gear units PRand PU must be axially elongated, and because this member transmits thereduced speed rotation, its thickness must be increased so as towithstand the transmitted torque, and therefore its weight must also beincreased. Therefore, an object of the present invention is to providean automatic transmission that can reduce the distance between theplanetary gear units PU and PR, and to thereby minimize the weight ofthe transmitting member.

In this fourteenth embodiment, in particular, the clutch C1 is disposedon the side of the second planetary gear unit PR opposite the firstplanetary gear unit PU, and therefore, providing a clutch betweenplanetary gear units PR and PU is not necessary, and the length of thetransmitting member 30 can be made that much shorter. Therefore, weightof the automatic transmission as a whole can be reduced.

Fifteenth Embodiment

The fifteenth embodiment, which is a partial modification of thepreviously described embodiments will now be described with reference toFIG. 21 through FIG. 23. Components of the fifteenth embodiment whichare the same as those of the first embodiment are denoted by the samereference numerals, and description thereof will not be repeated here,except for modifications.

As illustrated in FIG. 21, the automatic transmission 1 ₁₅ of thefifteenth embodiment comprises a first planetary gear unit PU and asecond planetary gear unit PR on the input shaft 2, similar to theautomatic transmission 1 ₁ of the first embodiment. The first planetarygear unit PU comprises a first simple planetary gear unit SP2 and asecond simple planetary unit SP3, and is a Simpson-type planetary gearunit comprising a sun gear S2 and a sun gear S3 that are linkedtogether, a carrier CR3 and a ring gear R2 that are linked together, aring gear R3, and a carrier CR2, as the four rotary components. Further,the second planetary gear unit PR is a double pinion planetary gear unitcomprising a carrier CR1, a pinion P1 b which is meshed with a ring gearR1 and a pinion P1 a which is meshed with a sun gear S1, wherein thepinions are also meshed with one another.

On the input shaft 2 is mounted a multi-disc clutch C1, which comprisesa hydraulic servo 11, friction plates 71, a clutch drum 121, and a hubunit 122. The oil chamber of this hydraulic servo 11 is connected to anoil line 91 of the boss 3 a which forms a sleeve around one end of theinput shaft 2 and this oil line 91 is connected to an oil pressurecontrol unit, not illustrated. In other words, an oil line from the oilpressure control unit, not illustrated, to the oil chamber of thehydraulic servo 11 is connected simply by providing one set of sealrings 81 which form a seal between the boss 3 a and the drum 121.

The input shaft 2 is connected to the clutch drum 121, and the innersurface of this drum 121 is splined to the friction plates 71 of theclutch C1 which are intermeshed with friction plates splined to the hubunit 122 which, in turn, is connected to the sun gear S2.

At the other end (the left of the diagram) of the input shaft 2 is amulti-disc clutch C2 which comprises a hydraulic servo 12, frictionplates 72, a clutch drum 123, and a hub unit 124 linked to a carrierCR3. At the outer circumference is a multi-disc clutch C3 whichcomprises a hydraulic servo 13, friction plates 73, and a clutch drum125. Further, radially outward of the clutch drum 125 is a multi-discbrake B1 which comprises a hydraulic servo 14 and friction plates 74.

The oil chamber of this hydraulic servo 12 is connected to an oil line 2b which is formed on the input shaft 2, and this oil line 2 b extendsalong the edge of the case 3 that is opposite the above-mentioned boss 3a, and is connected to the oil line 93 of the boss 3 b which forms asleeve around the input shaft 2. Therefore, an oil line from the oilpressure control unit, not illustrated, to the oil chamber of thehydraulic servo 12, is connected simply by providing one set of sealrings 82 to form a seal between the input shaft 2 and the clutch drum23.

Further, the oil chamber of the hydraulic servo 13 is connected to anoil line 94 of the boss 3 b, which oil line 94 is connected to the oilpressure control unit. In other words, for the above-mentioned hydraulicservo 13, an oil line from the oil pressure control unit to the oilchamber of the hydraulic servo 13 is connected by one set of seal rings84 between the boss 3 b and the clutch drum 125.

The input shaft 2 is connected to the drum-shaped member 123 on the leftside of the diagram, and the inner surface of this drum-shaped member123 is splined to the friction plates 72 of the clutch C2 which isoperated by the hydraulic servo 12. The friction plates 72 areintermeshed with friction plates splined to the hub unit 124, which isconnected to the carrier CR3.

The clutch drum 125 is rotatably supported by the boss 3 b, and theouter surface of a front edge of this clutch drum 125 is splined tofriction plates 74 of the brake B1 which is operated by hydraulic servo14. The inner surface of the front portion of drum 125 is splined to thefriction plates 73 of the clutch C3 which is operated by the hydraulicservo 13. The friction plates 73 are intermeshed with friction platessplined to the ring gear R1.

The carrier CR1 supports a pinion P1 a and a pinion P1 b. Pinion P1 bmeshes with the ring gear R1, and pinion P1 a meshes with the sun gearS1 which is connected to the input shaft 2. Carrier CR1, in turn, issecured to the boss 3 b of the case 3 via a side plate, and ring gear R1is rotatably supported by a supporting element 126 fixed to the boss 3b.

The drum 125 is connected to a transmitting member 130 that receives therotation of the ring gear R1 when the clutch C3 is engaged, and,further, the other end of this transmitting member 130 is connected thering gear R3 of the second simple planetary gearing SP3 of the firstplanetary gear unit PU.

On the outer side of the first simple planetary gearing SP2 is a one-wayclutch F1, and the inner race of this one-way clutch F1 is connected tothe hub unit 128 which, in turn, is connected to the ring gear R2 of thefirst simple planetary gearing SP1. Further, on the outer side of thisring gear R2 is a brake B2 comprising a hydraulic servo 15 and frictionplates 75. The friction plates 75 are intermeshed with friction platessplined to the ring gear R2 and the hub unit 128, and are splined to theinner surface of the case 3. Thus, ring gear R2 can be held againstrotation by engagement of the brake B2.

Further, the carrier CR3 supports a pinion P3 which is meshed with theinner surface of the ring gear R3 and with the sun gear S3. The carrierCR3 is also linked to the ring gear R2. The carrier CR2 supports apinion P2 which is meshed with the inner surface of the ring gear R2 andwith sun gear S2. Also, this carrier CR2 is linked to the counter gear 5via side plate 127.

The second planetary gear unit PR and the clutches C2 and C3 are locatedon one side of the first planetary gear unit PU, and the clutch C1 andthe counter gear 5 are located on the axially opposite side (right sideof the diagram) of the first planetary gear unit PU. Further, the clutchC2 is disposed radially inward of the clutch C3, and radially inward ofthe transmitting member 130. Further, the brake B1 is disposed radiallyoutward of the second planetary gear unit PR, and the brake B2 isdisposed radially outward of the first planetary gear unit PU.

The operations of the automatic transmission 1 ₁₅ of this fifteenthembodiment will now be described with reference to FIG. 21, FIG. 22, andFIG. 23 below. The vertical axes of the speed line diagram illustratedin FIG. 23 indicate the speeds of each rotary component, and thehorizontal axis indicates the corresponding gear ratio of the rotarycomponents. In the first planetary gear unit PU section of this speedline diagram, the vertical axis to the farthest horizontal edge (theright side of FIG. 23) corresponds to ring gear R3, and moving to theleft within the diagram, the vertical axes correspond to the ring gearR2 and the carrier CR3, the carrier CR2, and the sun gear S2 and the sungear S3. In the second planetary gear unit PR section of this speed linediagram, the vertical axis to the farthest horizontal edge (the rightside of FIG. 23) corresponds to sun gear S1, and moving to the leftwithin the diagram, the vertical axes correspond to the ring gear R1 andthe carrier CR1. Further, the widths between these vertical axes areinversely proportional to the number of teeth of each of the sun gearsS1, S2, S3, and to the number of teeth of each of the ring gears R1, R3.The horizontal dotted line in the diagram illustrates the speed ofrotation transmitted by the transmitting member 130.

As illustrated in FIG. 21, the rotation of input shaft 2 is input to thesun gears S2 and S3, by engaging the clutch C1. The rotation of inputshaft 2 is also input to the carrier CR3 and ring gear R2, by engagingthe clutch C2. The carrier CR3 and ring gear R2 can be fixed againstrotation by engagement of the brake B2 and, further, their rotation canbe limited to one direction by the one-way clutch F1.

When the rotation of the input shaft 2 is input to the sun gear S1, andthe carrier CR1 is fixed to the case 3, the ring gear R1 rotates at areduced speed. The reduced speed rotation of the ring gear R1 is inputto the ring gear R3 via the transmitting member 130 by engagement of theclutch C3. Further, the ring gear R3 may be fixed against rotation byengagement of the brake B1. The rotation of the carrier CR2 is output tothe counter gear 5 and to the drive wheels via this counter gear 5, acounter shaft (not illustrated), and a differential unit.

In first speed forward within the D (drive) range, as illustrated inFIG. 22, the clutch C1 and the one-way clutch F1 are engaged. Then, asillustrated in FIG. 23, the rotation of input shaft 2 is input to thesun gears S2 and S3 via the clutch C1, and the rotation of the carrierCR3 and the ring gear R2 is limited to one direction (the direction offorward rotation). With rotation of the input shaft 2 input to the sungear S2 and the reduced speed rotation output to the carrier CR2 via thefixed ring gear R2, the forward rotation for first speed forward isoutput from the counter gear 5. At this time, within the secondplanetary gear unit PR, the reduced speed rotation is output to the ringgear R3 via the sun gear S1 (which receives the rotation of the inputshaft 2) and the fixed carrier CR1; however, the transmitting member 130does not transmit torque because the clutch C3 is released. Further,when downshifting (when coasting), the brake B2 is engaged and the ringgear R2 is fixed to maintain first speed forward while preventingforward rotation of ring gear R2.

Further, in first speed forward, the one-way clutch F1 prevents the ringgear R2 from rotating in reverse while allowing forward rotation, andtherefore, switching from a non-driving range to a driving range andachieving first speed forward can be accomplished more smoothly by theautomatic engaging of the one-way clutch.

In second speed forward within D (drive) range, as illustrated in FIG.22, the clutch C1 and brake B1 are engaged. As illustrated in FIG. 23,the rotation of input shaft 2 is input to the sun gears S2 and S3 viathe clutch C1, and the ring gear R3 is fixed against rotation. Also,reduced speed rotation is output to the carrier CR3 and the ring gear R2via the rotation of the input shaft 2 that is input to the sun gear S3and the fixed ring gear R3. Rotation at a speed reduced from that of theabove-mentioned first speed forward is input to the carrier CR2, via therotation of the input shaft 2 input to the sun gear S2 and the reducedspeed rotation input to ring gear R2, and the forward rotation forsecond speed forward is output from the counter gear 5. At this time,within the second planetary gear unit PR, the reduced speed rotation isoutput to the ring gear R3 via the sun gear S1, which receives therotation of the input shaft 2, and the fixed carrier CR1; however, thetransmitting member 130 does not transmit torque because the clutch C3is released.

In third speed forward within the D (drive) range, as illustrated inFIG. 22, the clutches C1 and C3 are engaged. As illustrated in FIG. 23,the rotation of input shaft 2 is input to the sun gear S1 and to thering gear R1 through the fixed carrier CR1. The ring gear R1, nowrotating at a reduced speed, outputs its reduced speed rotation to thering gear R3 via the transmitting member 130, with the clutch C3engaged. The rotation of the input shaft 2 is also input to the sun gearS2, and a slightly greater, but reduced, speed rotation is output to thecarrier CR3 and to the ring gear R2 via sun gear S3 and the reducedspeed rotation of the ring gear R3. A reduced speed rotation greaterthan that of the above-mentioned second speed forward is output to thecarrier CR2 from the rotation of the input shaft 2 input to the sun gearS2 and the slightly greater but reduced speed rotation input to ringgear R2, and the forward rotation for third speed forward is output fromthe counter gear 5. In this case, because the ring gear R1 and the ringgear R3 are rotating at a reduced speed, the transmitting member 130carries a relatively large torque.

In fourth speed forward within D (drive) range, as illustrated in FIG.22, the clutches C1 and C2 are engaged. Then, as illustrated in FIG. 23,the rotation of input shaft 2 is input to the sun gears S2 and S3 viathe clutch C1, and to the carrier CR3 and the ring gear R2 via theclutch C2 to establish a directly coupled state wherein the rotation ofthe input shaft 2 is output as is into the carrier CR2, and the forwardrotation for fourth speed forward is output from the counter gear 5. Atthis time, within the second planetary gear unit PR, the reduced speedrotation is output to the ring gear R3 via the sun gear S1 (whichreceives the rotation of the input shaft 2) and the fixed carrier CR1;however, the transmitting member 130 does not transmit torque becausethe clutch C3 is released.

In fifth speed forward within the D (drive) range, as illustrated inFIG. 22, the clutches C1 and C3 are engaged. Then, as illustrated inFIG. 23, the rotation of input shaft 2 is input to the sun gear S1, andthe ring gear R1 reduces the speed of rotation received through thefixed carrier CR1. Further, the reduced speed rotation of this ring gearR1 is output to the ring gear R3 via the transmitting member 130, withthe clutch C3 engaged. The rotation of the input shaft 2 is also inputto the carrier CR3 and the ring gear R2, and overdrive speed rotation isoutput to the sun gears S2 and S3. Overdrive rotation is also output tothe carrier CR2 from the rotation of the input shaft 2 input to the ringgear R2 and to sun gear S2, and the forward rotation for fifth speedforward is output from the counter gear 5. In this case, because thering gear R1 and the ring gear R3 are rotating at a reduced speed, thetransmitting member 130 transmits a relatively large torque.

In sixth speed forward within the D (drive) range, as illustrated inFIG. 22, the clutch C2 and the brake B1 are engaged. Then, asillustrated in FIG. 23, the rotation of the input shaft 2 is input tothe carrier CR3 and to the ring gear R2 via the clutch C2, and the ringgear R3 is fixed by engagement of the brake B1. This produces overdriverotation (even greater than that of the above-mentioned fifth speedforward), which is output to the sun gears S3 and S2. From the rotationof the input shaft 2 input to the ring gear R2 and the increased speedrotation input to sun gear S2, a raised speed rotation, higher than thatof the above-mentioned fifth speed forward, is output as sixth speedforward from the counter gear 5. At this time, within the secondplanetary gear unit PR, the reduced speed rotation is output to the ringgear R3 via the sun gear S1 (which receives the rotation of the inputshaft 2) and the fixed carrier CR1; however, the transmitting member 130does not transmit torque, because the clutch C3 is released.

In first speed reverse, as illustrated in FIG. 22, the clutch C3 and thebrake B2 are engaged. In this manner, as illustrated in FIG. 23, therotation of the input shaft 2 is input to the sun gear S1, and the ringgear R1 rotates at reduced speed rotation via the fixed carrier CR1.Further, because the clutch C3 is engaged, the reduced speed rotation ofring gear R1 is input to the ring gear R2 via the transmitting member130. Further, because the brake B2 is engaged, the carrier CR3 and thering gear R2 are fixed against rotation, and reverse rotation is outputto the sun gear S3 and the sun gear S3 because of the fixed carrier CR3and the reduced speed rotation of the ring gear R3. Reverse rotation isoutput to the carrier CR2, with ring gear R2 fixed and the reverserotation input to sun gear S2, and the rotation for first speed reverseis output from the counter gear 5. In reverse, similar to third speedforward and fifth speed forward, the ring gears R1 and R3 are rotatingat a reduced speed and, accordingly, the transmitting member 130transmits a relatively large torque.

In P (parking) range and N (neutral) range, the clutches C1, C2, and C3are released, the input shaft 2 is disconnected from the counter gear 5,and the automatic transmission 1 ₁₅ as a whole is in an idle state(neutral state).

In the automatic transmission 1 ₁₅ of this fifteenth embodiment, becausethe second planetary gear unit PR and the clutch C2 are located on oneside of the first planetary gear unit PU, and the clutch C1 is locatedon the axially opposite side of the first planetary gear unit PU, theplanetary gear units PR and PU can be located more closely together,compared to a transmission wherein, for example, two clutches C1 and C2are located between the planetary gear units PR and PU, and thetransmitting member 130 can be made relatively shorter. By doing so, theautomatic transmission can be made more compact and more lightweight.Further, because the inertia (inertial force) can be reduced, thecontrollability of the automatic transmission can be increased, and theoccurrence of speed change shock can be reduced. Further, compared tothe case wherein three clutches C1, C2, C3 are located on one side ofthe planetary gear unit PU, the oil lines (for example, 2 a, 2 b, 91,93, 94) that supply the hydraulic servos 11, 12, and 13 of theseclutches C1, C2, C3 can be easily constructed, the manufacturing processcan be simplified, and the costs can be reduced.

Because the hydraulic servos 11 and 12 are mounted on the input shaft 2,one set of seal rings 81 and 82 form a connection to the case 3 forsupply of oil to the oil lines 2 a and 2 b within input shaft 2, andtherefore oil can be supplied to the oil chambers of hydraulic servos 11and 12 without providing seal rings between, for example, the inputshaft 2 and the hydraulic servos 11 and 12. Further, hydraulic servo 13can receive supply of oil directly from the boss 3 b, i.e. withoutpassing through other units. Therefore, oil can be supplied simply byproviding one set of seal rings 81 and 82, 84 for each of the hydraulicservos 11, 12, and 13, sliding resistance from the seal rings can beminimized, and therefore the efficiency of the automatic transmissioncan be improved.

Further, because the clutch C2 is located radially inward of the clutchC3, the clutch C3, which must transmit a relatively large torque at thereduced speed, and its hydraulic servo 13 can have an increaseddiameter. In particular, the pressure-receiving area of the oil chamberof the hydraulic servo 13 can be enlarged, and the torque transmissioncapacity of this clutch C3 can be increased. Further, the clutch C2 canbe designed have a smaller torque transmission capacity than the clutchC3, and therefore the automatic transmission can be made more compact.

Further, the clutch C1 engages at the relatively slow to medium speedsof first speed forward, second speed forward, third speed forward, andfourth speed forward, and therefore when this clutch C1 is released atthe relatively high speeds, i.e. fifth speed forward, sixth speedforward, and first speed reverse, the hub unit 122 that connects thisclutch C1 and the sun gear S2 rotates at a relatively high speed or inreverse (see FIG. 3). Because in fifth speed forward and first speedreverse the transmitting member 130 rotates at a reduced speed, and insixth speed forward the transmitting member 130 may be fixed in somecases, the speeds of hub unit 122 and the transmitting member 130 candiffer. However, because clutch C1 is located on the side of the firstplanetary gear unit PU axially opposite the second planetary gear unitPR, the hub unit 122 and the transmitting member 130 can be spaced apartfrom one another. As compared with a transmission wherein, for example,these members are in contact due to a multi-axial configuration,decrease in efficiency of the automatic transmission resulting fromfriction and so forth from the relative rotation of those units can beavoided.

The automatic transmission 1 ₁₅ of this fifteenth embodiment is directlycoupled in fourth speed forward. Therefore, in fifth speed forward andsixth speed forward, the gear ratio can be a high ratio, andparticularly when the vehicle is running at a high speed, the enginespeed can be reduced, thereby allowing the vehicle to run more quietly.

The transmitting member linking the planetary gear units PR and PUrequires rigidity to withstand the reduced speed torque that ittransmits. A clutch that engages at a slow to medium speed and a clutchthat engages and disengages a reduced speed rotation on the inner sideof the transmitting member must have a large capacity, and therefore adiameter corresponding to this capacity becomes necessary. Therefore, ifthe transmitting member passes on the outer circumferential side of thistype of clutch, an even larger diameter becomes necessary, the linkingmember must be enlarged, and the automatic transmission as a whole isincreased in diameter. Therefore an object of the present embodiment isto allow reduction of the diameter, and to provide a more compactautomatic transmission.

According to the present embodiment, enlargement of the diameter of thelinking member is avoided by locating a clutch C2 with a small capacityon the inner side of the transmitting member 130.

Sixteenth Embodiment

The sixteenth embodiment, which is a partial modification of thefifteenth embodiment will now be described with reference to FIGS. 24through 26. Components of the sixteenth embodiment which are the same asthose of the fifteenth embodiment are denoted by the same referencenumerals, and description thereof will not be repeated, except formodifications.

As illustrated in FIG. 24, the automatic transmission 1 ₁₆ of thesixteenth embodiment differs with regard to the configuration of thesecond planetary gear unit PR and the clutch C3, as compared to theautomatic transmission 1 ₁₅ of the fifteenth embodiment (see FIG. 21).

In this sixteenth embodiment the clutch C3 is located on the planetarygear unit PU side (left side of diagram) of the second planetary gearunit PR. The inner surface of a front portion of the drum 125 of thisclutch C3 is splined to the friction plates 73, which are intermeshedwith friction plates splined to the hub unit 126. The drum 125 isconnected to the input shaft 2, and the hub unit 126 is connected to thesun gear S1. The clutch C2 includes a hydraulic servo 12, frictionplates 72, a drum 123, and a hub unit 124 and is located radially inwardof the clutch C3. Thus, clutch C2 is enclosed within the hub unit 126.

On radially outer side of the second planetary gear unit PR is amulti-disc brake B1 that comprises a hydraulic servo 14 and frictionplates 74. The side plate of the carrier CR1 of this second planetarygear unit PR is fixed to and supported by the case 3. Further, the ringgear R1 is connected to the transmitting member 130, and the frictionplates 74 of the brake B1 are intermeshed with friction plates splinedto the outer circumferential surface of transmitting member 130 which isconnected to the ring gear R3.

The operations of the automatic transmission 1 ₁₆ will now be describedwith reference to FIG. 24, FIG. 25, and FIG. 26. As with theabove-mentioned first embodiment, the vertical axes of the speed linediagram illustrated in FIG. 26 indicate the speed of each rotarycomponent, and the horizontal axis indicates the corresponding gearratio of these rotary components. Further, regarding the planetary gearunit PU section of this speed line diagram, the vertical axis to thefarthest horizontal edge (the right side of FIG. 26) corresponds to ringgear R3, and moving to the left within the diagram, the vertical axescorrespond to the ring gear R2 and the carrier CR3, the carrier CR2, andthe sun gear S2 and the sun gear S3. Further, regarding the secondplanetary gear unit PR section of this speed line diagram, the verticalaxis to the farthest horizontal edge (the right side of FIG. 26)corresponds to sun gear S1, and moving to the left within the diagram,the vertical axes correspond to the ring gear R1 and the carrier CR1.Further, the widths between these vertical axes are inverselyproportional to the number of teeth of each of the sun gears S1, S2, S3,and to the number of teeth of each of the ring gears R1, R3. Again, thedotted horizontal line represents the rotation transmitted by thetransmitting member 130.

As illustrated in FIG. 24, by engaging the clutch C3, the rotation ofthe input shaft 2 is input to the sun gear S1. Further, the carrier CR1is fixed to the case 3, and the ring gear R1 rotates at a reduced speedbased on the rotation of the input shaft 2 input to sun gear S1. Inother words, by engaging the clutch C3, the reduced speed rotation ofthe ring gear R1 is input to the ring gear R3 via the transmittingmember 130.

As illustrated in FIG. 25 and FIG. 26, within the second planetary gearunit PR, in third speed forward, fifth speed forward, and first speedreverse, the rotation of the input shaft 2 is input to the sun gear S1by engaging the clutch C3, the reduced speed rotation is output to thering gear R3 through the fixed carrier CR1, and the reduced speedrotation is input to the ring gear R3 via the transmitting member 130.At this time, the ring gear R1 and the ring gear R3 are rotating at areduced speed, and therefore the transmitting member 130 transmits arelatively large torque. On the other hand, in first speed forward,second speed forward, fourth speed forward, and sixth speed forward, therotation of the ring gear R3 is input to the ring gear R1 via thetransmitting member 130, and further, because clutch C3 is released, asillustrated in FIG. 7, the sun gear S1 rotates in accordance with thespeed of ring gear R1.

The operations of the second planetary gear unit PR are similar to thoseof the above-described fifteenth embodiment (see FIG. 22 and FIG. 23),and accordingly description thereof will be omitted.

In the automatic transmission 1 ₁₆ of this sixteenth embodiment, becausethe second planetary gear unit PR and the clutch C2 are located on oneside of the first planetary gear unit PU, and the clutch C1 is locatedon the axially opposite side of the first planetary gear unit PU, theplanetary gear units PR and PU can be located more closely together,compared to a transmission wherein, for example, two clutches C1 and C2are located between the planetary gear units PR and PU, and thetransmitting member 130 can be made relatively shorter. Thus, theautomatic transmission can be made more compact and more lightweight.Further, because the inertia (inertial force) can be reduced, thecontrollability of the automatic transmission can be increased, and theoccurrence of speed change shock can be reduced. Further, compared to atransmission wherein three clutches C1, C2, C3 are located on one sideof the first planetary gear unit PU, the oil lines (for example, 2 a, 2b, 91, 93, 94) that supply the hydraulic servos 11, 12, and 13 of theseclutches C1, C2, C3 can be more easily constructed, the manufacturingprocess can be simplified and the costs can be reduced.

Further, since the hydraulic servos 11 and 12 are mounted on the inputshaft 2, one set of seal rings 81 and 82 seal the case 3 to the inputshaft 2 for supply of oil to the oil lines 2 a and 2 b, and thereforeoil can be supplied to the oil chambers of hydraulic servos 11 and 12without providing seal rings between, for example, the input shaft 2 andthe hydraulic servos 11 and 12. Further, the hydraulic servo 13 canreceive supply of oil directly from the boss 3 a extended from the case3, without passing through other elements. Therefore, oil can besupplied simply by providing one set of seal rings 81 and 82, 84 foreach of the hydraulic servos 11, 12, and 13, sliding resistance from theseal rings can be minimized, and therefore the efficiency of theautomatic transmission can be improved.

Further, the clutch C1 engages at the relatively slow to medium speedsof first speed forward, second speed forward, third speed forward, andfourth speed forward, and therefore when this clutch C1 is released atthe relatively high speeds of fifth speed forward, sixth speed forward,and first speed reverse, the hub unit 122 that connects clutch C1 andthe sun gear S2 rotates at a relatively high speed or in reverse (seeFIG. 3). On the other hand, in the fifth speed forward and first speedreverse the transmitting member 130 rotates at a reduced speed, and insixth speed forward the transmitting member 130 may be fixed in somecases, whereby the speeds of the hub unit 122 and the transmittingmember 130 may differ. However, because clutch C1 is located on the sideof the first planetary gear unit PU opposite the second planetary gearunit PR, the hub unit 122 and the transmitting member 130 can be spacedapart from one another. As compared with a transmission wherein, forexample, these members are in contact due to a multi-axialconfiguration, decreased efficiency of the automatic transmissionresulting from friction and so forth from the relative rotation of thoseunits can be avoided.

Further, if the clutch C3 is placed between the ring gear R1 and the sungear S3, for example, the reduced speed rotation must be engaged anddisengaged, and the clutch C3 must be relatively large, but by placingclutch C3 between the input shaft 2 and the sun gear S1, the engagingand disengaging of clutch C3 indirectly controls transmission of thereduced speed rotation from the ring gear R1 of the second planetarygear unit PR, the clutch C3 can be made more compact, and therefore theautomatic transmission can be made more compact.

Further, the automatic transmission 1 ₁₆ of this sixteenth embodiment isdirectly coupled in fourth speed forward. Therefore, in fifth speedforward and sixth speed forward, the gear ratio can be a high ratio, andwhen the vehicle is running at a high speed, the engine speed can bereduced, and the vehicle can run more quietly at a high speed.

If a clutch is located between the planetary gear units PR and PU, thelength of the transmitting member that links the planetary gear units PRand PU must be axially elongated, and since this transmitting membertransmits the reduced speed rotation, the thickness of the transmittingmember must be increased, and therefore the weight also increases.Therefore an object of the present invention is to provide an automatictransmission that can shorten the distance between the planetary gearunits and thereby reduce the weight.

In the present embodiment, the clutch C2 is disposed on the side of thefirst planetary gear unit PU opposite the second planetary gear unit PR,and therefore a clutch between the planetary gear units PR and PU is notnecessary, and the length of the transmitting member 130 can be shorter.Therefore, the weight of the automatic transmission as a whole can bereduced.

Seventeenth Embodiment

A seventeenth embodiment, which is a partial modification of thefifteenth embodiment will now be described with reference to FIG. 27through FIG. 29. Components of the seventeenth embodiment which are thesame as those of the fifteenth embodiment are denoted by the samereference numerals, and description thereof omitted, except for themodifications.

As FIG. 27 illustrates, the automatic transmission 1 ₁₇ of theseventeenth embodiment differs from the fifteenth embodiment withrespect to the configuration of the clutch C2, and in use of a brake B3instead of a clutch C3, whereby the carrier CR1 of the second planetarygear unit PR can be fixed by the brake B3.

Within the automatic transmission 1 ₁₇, the brake B3 is located on thesecond planetary gear unit PR, on the side (left side on the diagram)opposite the planetary gear unit PU. This brake B3 comprises a hydraulicservo 16, friction plates 76, and a hub unit 133. Further, the clutchC2, comprising a hydraulic servo 12, friction plates 72, a drum 123, anda hub unit 124, is located radially inward of the brake B3 and withinthe hub unit 133. The hub unit 133 of brake B3 is connected to one sideplate of the carrier CR1, and the other side plate of the carrier CR1 isrotatably supported by the input shaft 2. Further, the sun gear S1 isconnected to the input shaft 2 via the drum 123 of the clutch C2. Thefriction plates 74 of the brake B1 are intermeshed with friction platessplined to the outer circumferential surface of the ring gear R1, andthis ring gear R1 is connected by the transmitting member 130 to the sungear S3.

The operations of the automatic transmission 1 ₁₇ will now be describedwith reference to FIG. 27, FIG. 28, and FIG. 29 below. Now, as with theabove-mentioned first embodiment, the vertical axes of the speed linediagram illustrated in FIG. 29 indicate the speeds of each rotarycomponent, and the horizontal axis indicates the corresponding gearratio of these rotary components. In the planetary gear unit PU sectionof this speed line diagram, the vertical axis to the farthest horizontaledge (the right side of FIG. 29) corresponds to ring gear R3, and movingto the left within the diagram, the vertical axes correspond to the ringgear R2 and the carrier CR3, the carrier CR2, and the sun gears S2 andS3. Further, in the second planetary gear unit PR section of this speedline diagram, the vertical axis to the farthest horizontal edge (theright side of FIG. 29) corresponds to sun gear S1, and moving to theleft within the diagram, the vertical axes correspond to the ring gearR1 and the carrier CR1. Further, the widths between these vertical axesare inversely proportional to the number of teeth of each of the sungears S1, S2, S3, and to the number of teeth of each of the ring gearsR1, R3. Again, the horizontal dotted line in the diagram represents therotation transmitted by the transmitting member 130.

As FIG. 27 illustrates, by engaging the brake B3, the carrier CR1 isfixed to the case 3. Further, the rotation of the input shaft 2 is inputto the sun gear S1, and the ring gear R1 rotates at reduced speedrotation based on the rotation of input shaft 2 which is input to thissun gear S1, with the carrier CR1 fixed. In other words, by engaging thebrake B3, the reduced speed rotation of the ring gear R3 is input to thesun gear S3 via the transmitting member 130.

As FIG. 28 and FIG. 29 illustrate, with regard to the second planetarygear unit PR, in third speed forward, fifth speed forward, and firstspeed reverse, the rotation of the input shaft 2 is input to the sungear S1 by engagement of the brake B3 to fix the carrier CR1, and thereduced speed rotation is output to the ring gear R3 by the rotation ofthe sun gear S1 which receives input of the rotation of the input shaft2, and the reduced speed rotation is input to the sun gear S3 via thetransmitting member 130. In this case, the ring gears R1 and R3 arerotating at the reduced speed, and therefore the transmitting member 130transmits a relatively large torque. On the other hand, at first speedforward, second speed forward, fourth speed forward, and sixth speedforward, the rotation of the ring gear R3 is input to the ring gear R1via the transmitting member 130, and further, because the brake B3 isreleased, as FIG. 29 illustrates, the carrier CR1 rotates within thespeed range of this ring gear R1 and the sun gear S1.

The operations of the second planetary gear unit PR are similar to thoseof the fifteenth embodiment (see FIG. 22 and FIG. 23), and accordinglydescription thereof will not be repeated here.

In the automatic transmission 1 ₁₇ of this seventeenth embodiment, dueto the second planetary gear unit PR and the clutch C2 being located onone side of the planetary gear unit PU, and the clutch C1 being locatedon the axially opposite side of the planetary gear unit PU, the secondplanetary gear unit PR and the planetary gear unit PU can be locatedmore closely together, as compared to a transmission wherein, forexample, two clutches C1 and C2 are disposed between the planetary gearunits PR and PU, and the transmitting member 130 can be made relativelyshorter. By doing so, the automatic transmission can be made morecompact and more lightweight. Further, because the inertia (inertialforce) can be reduced, the controllability of the automatic transmissioncan be increased, and the occurrence of speed change shock can bereduced.

Further, since the hydraulic servos 11 and 12 are mounted on the inputshaft 2, one set of the seal rings 81 and 82 seal the case 3 to theinput shaft 2 for supply of oil to the oil lines 2 a and 2 b providedwithin input shaft 2, and therefore oil can be supplied to the oilchambers of hydraulic servos 11 and 12 without providing seal ringsbetween, for example, the input shaft 2 and the hydraulic servos 11 and12. Therefore, oil can be supplied simply by providing one set of theseal rings 81 and 82 for each of the hydraulic servos 11 and 12, slidingresistance from the seal rings can be minimized, and therefore theefficiency of the automatic transmission can be improved.

Further, the clutch C1 engages at the relatively slow to medium speedsof first speed forward, second speed forward, third speed forward, andfourth speed forward, and therefore when this clutch C1 is released atthe relatively high speeds of fifth speed forward, sixth speed forward,or first speed reverse, the hub unit 122 that connects this clutch C1and the sun gear S2 rotates at a relatively high speed or in reverse(see FIG. 3). On the other hand, in fifth speed forward and first speedreverse the transmitting member 130 rotates at reduced speed, and insixth speed forward the transmitting member 130 may be fixed in somecases, and accordingly the speeds of the hub unit 122 and thetransmitting member 130 can differ. However, because clutch C1 islocated on the side of the first planetary gear unit PU opposite thesecond planetary gear unit PR, the hub unit 122 and the transmittingmember 130 can be spaced apart from one another. In comparison with atransmission wherein, for example, these members are in contact due to amulti-axial configuration, decreased efficiency of the automatictransmission resulting from friction and so forth from the relativerotation of those units can be avoided.

Further, since the reduced speed rotation output to the first planetarygear unit PU from the second planetary gear unit PR is engaged anddisengaged by the brake B3, the number of components (for example drumsand so forth) can be reduced as compared to an embodiment including, forexample, clutch C3. Further, the brake B3 can receive oil supplydirectly from the case 3, and therefore the configuration of the oilline can be simplified as compared to the case wherein, for example, aclutch C3 is provided.

The automatic transmission 1 ₁₇ of this seventeenth embodiment isdirectly coupled in fourth speed forward. Therefore, in fifth speedforward and sixth speed forward, the gear ratio can be a high ratio, andparticularly when the vehicle is running at a high speed, the enginespeed can be reduced, whereby the vehicle will run more quietly at ahigh speed.

In this seventeenth embodiment, because the clutch C2 is disposed on theside of the first planetary gear unit PU opposite the second planetarygear unit PR, provision of a clutch between the second planetary gearunit PR and the first planetary gear unit PU is not necessary, and thelength of the transmitting member 130 can be shorter. Therefore, theweight of the automatic transmission as a whole can be less.

Eighteenth Embodiment

An eighteenth embodiment, which is a partial modification of the firstthrough the seventeenth embodiments will now be described, withreference to FIG. 30 through FIG. 32. Components of the eighteenthembodiment which are the same as those of the first embodiment aredenoted by the same reference numerals, and description will be omitted,except for modifications.

As illustrated in FIG. 30, the automatic transmission 1 ₁₈ of theeighteenth embodiment comprises a first planetary gear unit PU and asecond planetary PR on the input shaft 2. The first planetary gear unitPU is a multiple type planetary gear unit, which comprises a sun gearS2, a carrier CR2, a ring gear R2, and a sun gear S3, a total of fourrotary components. The carrier CR2 supports a long pinion PL, thatmeshes with the sun gear S3 and the ring gear R2, and a short pinion PSthat meshes with the sun gear S3, with pinions PL and PS meshed one toanother. Further, the second planetary gear unit PR is a double pinionplanetary gear unit that has a carrier CR1 supporting a pinion Pb, whichis meshed with a ring gear R1, and a pinion Pa, which is meshed with asun gear S2, with the pinions Pa and Pb meshed one to another.

On the input shaft 2 is a multi-disc clutch (second clutch) C2 on theinner circumference side, which comprises a hydraulic servo 12, frictionplates 72, a clutch drum 223, and a hub unit 224 linked to the sun gearS2. A multi-disc brake B2, located on the outer circumference side,comprises a hydraulic servo 15, and friction plates 75 that areintermeshed with friction plates splined to the hub unit 224.

The oil chamber of this hydraulic servo 12 extends from one end of thecase 3, and is connected to an oil line 91 of the boss 3 a which isformed as a sleeve on the input shaft 2. Also, this oil line 91 connectsto an oil pressure control unit not illustrated. Because the hydraulicservo 12 is mounted on the boss 3 a, an oil line from the oil pressurecontrol unit, not illustrated, is connected to the oil chamber of thehydraulic servo 12 by one set of seal rings 81 which provide a sealbetween boss unit 3 a and the clutch drum 223.

Further, the above-mentioned input shaft 2 is connected to the clutchdrum 223 and the inner surface of a front portion of this drum 223 issplined to friction plates 72 of the clutch C2 which is operated by thehydraulic servo 12. Further, hub unit 224 is connected to the sun gearS2. Further, the brake B2 has friction plates 75 intermeshed withfriction plates splined to the outer circumferential surface of the drum224, engaged by operation of hydraulic servo 15.

At the other end (the left of the diagram) of the input shaft 2 is amulti-disc clutch (first clutch) C3 which comprises a hydraulic servo13, friction plates 73, a clutch drum 225, and a hub unit 226. Frictionplates 73 are splined to the inner surface of a front portion of theclutch drum 225, and are intermeshed with friction plates splined to theouter surface of a front portion of the hub unit 226 which is connectedto the carrier CR2.

The oil chamber of this hydraulic servo 13 is connected through an oilline 2 b which is formed on the input shaft 2 to oil line 93 of the boss3 b which, in turn, is connected to the oil pressure control unit.Therefore, by providing one set of seal rings 81 to seal between theboss 3 b and the drum 225, an oil line from the oil pressure controldevice is connected to the oil chamber of the hydraulic servo 13.

Mounted on the boss 3 b is a multi-disc clutch (third clutch) C1comprising a hydraulic servo 11, friction plates 71, and a drum 221. Theoil chamber of the hydraulic servo 11 is connected to the oil line 94 ofthe boss unit 3 b, and through oil line 94 to the oil pressure controlunit.

The boss unit 3 b rotatably supports the drum 221 and a front portion ofthe inner surface of drum 221 is splined to the friction plates 71 ofthe clutch C1 engaged by the hydraulic servo 11. Around the outercircumference of this clutch C1 is a hub unit 222 on which is formed thering gear R1. This hub unit 222 is rotatably supported by the inputshaft 2. Carrier CR1 supports a pinion Pb meshed with the ring gear R1and a pinion Pa meshed with the sun gear S1 which is connected to theinput shaft 2. This carrier CR1 is fixed to the boss 3 b of the case 3,via a side plate.

Also, the drum 221, to which the above-mentioned clutch C1 is splined,is rotatably supported by the boss 3 b, and is connected to atransmitting member 230 for transmitting the rotation of the ring gearR1, when the clutch C1 is engaged, to the sun gear S3 of the firstplanetary gear unit PU.

Around the outer circumference of the first planetary gear unit PU is amulti-disc brake B1 that comprises a hydraulic servo 14, friction plates74, and a hub unit 228. A side plate of the carrier CR2 of the firstplanetary gear unit PU is connected to a hub unit 228 to which frictionplates of the above-mentioned brake B1 are splined. Further, this hubunit 228 is connected to the inner race of a one-way clutch F1. Theshort pinion PS of this carrier CR2 meshes with the sun gear S3.Further, the sun gear S2 and ring gear R2 mesh with the long pinion PL.Transmitting member 227 connects one edge of ring gear R2 to the countergear 5.

As described above, the second planetary gear unit PR and the clutchesC1 and C3 are located on one side of the first planetary gear unit PU,and the clutch C2 and the counter gear 5 are located on the axiallyopposite side (right side of the diagram) of the first planetary gearunit PU. Further, the clutch C3 is arranged radially inward of theclutch C1 and radially inward of the transmitting member 230 thattransmits the output thereof. Further, brake B2 is located around theouter circumference of the clutch C2, and the brake B1 is located aroundthe outer circumference of the first planetary gear unit PU.

Operations of the automatic transmission 1 ₁₈ of the eighteenthembodiment will now be described with reference to FIG. 30, FIG. 31, andFIG. 32 below. The vertical axes of the speed line diagram illustratedin FIG. 32 indicate the speed of the various rotary components, and thehorizontal axis indicates the corresponding gear ratio of these rotarycomponents. Further, in the first planetary gear unit PU section of thisspeed line diagram, the vertical axis to the farthest horizontal edge(the right side of FIG. 32) corresponds to sun gear S3, and moving tothe left within the diagram, the vertical axes correspond to the ringgear R2, the carrier CR2, and the sun gear S2. Further, in the secondplanetary gear unit PR section of this speed line diagram, the verticalaxis to the farthest horizontal edge (the right side of FIG. 32)corresponds to the sun gear S1, and moving to the left within thediagram, the vertical axes correspond to the ring gear R1 and thecarrier CR1. Further, the widths between these vertical axes areinversely proportional to the number of teeth of each of the sun gearsS1, S2, S3, and to the number of teeth of each of the ring gears R1, R3.Again, the horizontal dotted line in the diagram represents the rotationtransmitted by the transmitting member 230.

As illustrated in FIG. 30, the rotation of the input shaft 2 is input tothe above-mentioned sun gear S2 by engaging the clutch C2, and the sungear S2 can be fixed by engagement of the brake B2. The rotation of theinput shaft 2 is input to the carrier CR2, by engaging the clutch C3,and the carrier C2 can be fixed by engagement of the brake B1. Further,rotation in one direction is controlled by the one-way clutch F1.

The sun gear S1 is connected to and receives input from the input shaft2, the carrier CR1 is connected to the case 3 whereby its rotation isfixed, and therefore the ring gear R1 rotates at a reduced speed.Further, by engaging the clutch C1, the reduced speed rotation of ringgear R1 is input to the sun gear S3. Also, the rotation of the ring gearR2 is output to the drive wheels through this counter gear 5, a countershaft unit not illustrated, and a differential unit.

In first speed forward within the D (drive) range, as illustrated inFIG. 31, the clutch C1 and the one-way clutch F1 are engaged. Then, asillustrated in FIG. 32, the reduced speed rotation of the ring gear R1is input to the sun gear S3 via the clutch C1 and the transmittingmember 230. Further, the rotation of the carrier CR2 is limited to onedirection (the forward rotation direction) by the one-way clutch F1.Then, the ring gear R2 rotates in first speed forward, derived from thereduced speed rotation input to the sun gear S2 and the fixed state ofcarrier CR2, and this rotation at first speed forward is output from thecounter gear 5.

For downshifting (when coasting), the brake B1 is engaged to fix thecarrier CR2, and the above-described state of first speed forward ismaintained while preventing forward rotation of carrier CR2. Further, infirst speed forward, the one-way clutch F1 prevents the carrier CR2 fromreverse rotation, and therefore, switching from a non-driving range to adriving range and establishing first speed forward can be accomplishedmore smoothly by the automatic engagement of the one-way clutch. In thisfirst speed forward, because the sun gear S3 and the ring gear R1 arerotating at a reduced speed, the transmitting member 230 transmits arelatively large torque.

In second speed forward within the D (drive) range, as illustrated inFIG. 31, the clutch C1 and the brake B2 are engaged. Then, asillustrated in FIG. 32, the reduced speed rotation of the ring gear R1is input to the sun gear S3 via the clutch C1 and the transmittingmember 230, and the rotation of the sun gear S2 is fixed by the brakeB2. By doing so, the carrier CR2 rotates at a slightly reduced speed,and driven by the reduced speed rotations input to the sun gear S3 andthis slightly reduced rotation of the carrier CR2, the ring gear R2rotates at second speed forward, which rotation is output to the countergear 5. Also in this case, because the sun gear S3 and the ring gear R1are rotating at a reduced speed, the transmitting member 230 transmits arelatively large torque.

In third speed forward within the D (drive) range, as illustrated inFIG. 31, the clutch C1 and the clutch C2 are engaged. Then, asillustrated in FIG. 32, the reduced speed rotation of the ring gear R1is input to the sun gear S3 via the clutch C1 and the transmittingmember 230, and also the rotation of the input shaft 2 is input to thesun gear S2 by engaging the clutch C2. Further, with the rotation of theinput shaft 2 input to the sun gear S2 and the reduced speed rotation ofthe sun gear S3, the carrier CR2 has slightly slower speed than the sungear S3. Further, from the input rotation of the sun gear S2 and thereduced speed rotation of the sun gear S3, the ring gear R2 is rotatedat third speed forward, and this rotation is output from the countergear 5. In this case also, because the sun gear S3 and the ring gear R1are rotating at a reduced speed, the transmitting member 230 transmits arelatively large torque.

In fourth speed forward within D (drive) range, as illustrated in FIG.31, the clutch C1 and the clutch C3 are engaged. Then, as illustrated inFIG. 32, the reduced speed rotation of the ring gear R2 is input to thesun gear S3 via the clutch C1 and the transmitting member 230, and alsothe rotation of the input shaft 2 is input to the carrier CR2 via theclutch C3. Then, driven by the rotation of input shaft 2 input to thecarrier CR2 and by the reduced speed rotation of the sun gear S3, thering gear R2 rotates at fourth speed forward, and this rotation isoutput from the counter gear 5. In this case also, because the sun gearS3 and the ring gear R1 are rotating at a reduced speed, thetransmitting member 230 transmits a relatively large torque.

In fifth speed forward within the D (drive) range, as illustrated inFIG. 31, the clutch C2 and the clutch C3 are engaged. Then, asillustrated in FIG. 32, the rotation of input shaft 2 is input to thecarrier CR2 via the clutch C3, and also the rotation of the input shaft2 is input to the sun gear S2 via the clutch C2. Then, with the rotationof the input shaft 2 input to the sun gear S2 and to the carrier CR2,the ring gear R2 is in a direct-connect rotating state, and rotates atfifth speed forward, i.e. at the same speed as the input shaft 2, andthis rotation is output from the counter gear 5.

In sixth speed forward within the D (drive) range, as illustrated inFIG. 31, the clutch C3 and the brake B2 are engaged. Then, asillustrated in FIG. 32, the rotation of the input shaft 2 is input tothe carrier CR2 via the clutch C3, and the sun gear S2 is fixed byengagement of the brake B2. Then, with the rotation of the input shaft 2input to the carrier CR2 and the sun gear S2 fixed, the ring gear R2rotates at sixth speed forward, and this rotation is output from thecounter gear 5.

In first speed reverse within the R (reverse) range, as illustrated inFIG. 31, the clutch C2 and the brake B1 are engaged. Then, asillustrated in FIG. 32, the rotation of the input shaft 2 is input tothe sun gear S2 by engaging the clutch C2, and the carrier CR2 is fixedby engagement of the brake B1. Then, with the rotation of the inputshaft 2 input to the sun gear S2 and the carrier CR2 fixed, the ringgear R2 rotates at first speed reverse, and this rotation is output tothe counter gear 5.

In P (parking) range and N (neutral) range, the clutches C1, C2, and C3are released, the input shaft 2 is disconnected from the counter gear 5,and the automatic transmission 1 ₁₈ as a whole is in an idle state(neutral state).

As described above, in the automatic transmission 1 ₁₈ of the eighteenthembodiment, because the second planetary gear unit PR and the clutch C3are located on one side of the first planetary gear unit PU, and theclutch C2 is located on the axially opposite side of the first planetarygear unit PU, the planetary gear units PR and PU can be located moreclosely together, as compared, for example, to an embodiment wherein twoclutches C2 and C3 are located between the planetary gear units PR andPU, and the transmitting member 230 can be relatively shorter. In thismanner, the automatic transmission can be made more compact and morelightweight. Further, because the inertia (inertial force) can bereduced, the controllability of the automatic transmission can beincreased, and the occurrence of speed change shock can be reduced.Further, compared to an embodiment wherein three clutches C1, C2, C3 arelocated on one side of the first planetary gear unit PU, the oil lines(for example, 2 b, 91, 93, 94) that supply the hydraulic servos 11, 12,and 13 of these clutches C1, C2, C3 can be more easily constructed, themanufacturing process can be simplified, and the costs can be reduced.

Further, since the hydraulic servo 13 is provided on the input shaft 2,one set of seal rings 82 form a seal between the case 3 and input shaft2 to supply oil through the oil line 2 b provided within input shaft 2to the oil chamber of hydraulic servo 13, without providing seal ringsbetween, for example, the input shaft 2 and the hydraulic servo 13.Further, hydraulic servos 11 and 12 can receive supply of oil directlyfrom the bosses 3 a, 3 b without passing through other components.Therefore, oil can be supplied simply by providing one set of seal rings81, 82, and 84 for each of the hydraulic servos 11, 12, and 13, andsliding resistance from the seal rings can be minimized, and thereforethe efficiency of the automatic transmission can be improved.

Further, since the clutch C3 is radially inward of the clutch C1, theclutch C1, which must transmit a relatively large torque at the reducedspeed, can be located on the outer circumference side, and this clutchC1 and the hydraulic servo 11 thereof can have an increased diameter.Particularly, the pressure-receiving area of the oil chamber of thehydraulic servo 11 can be enlarged, and the torque transmission capacityof this clutch C1 can thereby be increased. By designing the clutch C3to have a smaller torque transmission capacity as compared to the clutchC1, the automatic transmission can be made more compact.

Further, because clutch C2 engages in first speed reverse, the hub unit224 that connects this clutch C2 and the sun gear S2 rotate at the samespeed as the input shaft 2, while the transmitting member 230 rotates inthe opposite direction, and accordingly there is a great differencebetween the rotational speed of the transmitting member 230 and that ofthe hub unit 224, but due to clutch C2 being located on the side of thefirst planetary gear unit PU opposite the second planetary gear unit PR,the transmitting member 230 and the hub 224 can be spaced apart from oneanother. Compared to the case wherein, for example, those parts comeinto contact due to a multiple axis construction, the decreasedefficiency of the automatic transmission caused by the friction producedby the relative rotation between those parts can be avoided.

Further, the automatic transmission 1 ₁₈ according to this eighteenthembodiment is directly coupled in fifth speed forward. Therefore, atfirst speed forward and fourth speed forward, the gear ratio can be moreprecisely set, and particularly when the vehicle is running at a highspeed, the engine speed can be reduced and fuel economy of the vehiclewhile running at a low to medium speed can be improved.

The transmitting member for linking the planetary gear units PR and PUrequires rigidity to withstand the reduced speed torque that ittransmits. For example, in the case of a clutch that engages at a slowto medium speed and a clutch that engages and disengages reduced speedrotation located on the inner circumference side of the linking member,the clutch must have a large capacity, and therefore a diameterappropriately corresponding to this capacity becomes necessary.Therefore, in the event that the transmitting member is the type thatpasses on the radially outer circumference side of this clutch, an evenlarger diameter becomes necessary, the diameter of the transmittingmember must be further enlarged, and the automatic transmission as awhole must have a greater diameter. Therefore an object of the presentembodiment is to minimize the diameter, and to thereby provide a compactautomatic transmission.

According to the present embodiment, all clutches can be designed toavoid enlarging the diameter of the transmitting (linking) member, byproviding a clutch C3 with a small capacity on the radially inner sideof the transmitting member 230.

Nineteenth Embodiment

A nineteenth embodiment, which is a partial modification of theeighteenth embodiment will now be described with reference to FIG. 33through FIG. 36. Components of the nineteenth embodiment which are thesame as those of the eighteenth embodiment are denoted by the samereference numerals, and description thereof will not be repeated, exceptfor the modifications.

As FIG. 33 illustrates, the automatic transmission 1 ₁₉ of the automatictransmission of the nineteenth embodiment has the configuration of theclutch C2 modified, and the construction of the oil line for thehydraulic servo 12 is changed as compared to the automatic transmission1 ₁₈ of the eighteenth embodiment (see FIG. 30).

Within the automatic transmission 1 ₁₉, the clutch C1 is located on theside of the second planetary gear unit PR, opposite (left side on thediagram) the first planetary gear unit PU. A front portion of the innercircumferential surface of the drum 221 of this clutch C1 is splined tothe friction plates 71 which are intermeshed with friction platessplined to the hub unit 222. The drum 221 is connected to the inputshaft 2, and the hub unit 222 is connected to the sun gear S1 of thesecond planetary gear unit PR. The side plate of the carrier CR1 of thissecond planetary gear unit PR is fixed to and supported by the case 3.The ring gear R1 is connected through the transmitting member 230 to thesun gear S3. Further, the clutch C3, comprising a hydraulic servo 13,friction plates 73, a drum 225, and a hub unit 226, is located so as tobe enclosed within this transmitting member 230.

The oil chamber of this hydraulic servo 12 is connected to an oil line 2a which is formed on the input shaft 2, and this oil line 2 a isconnected to the oil line 91 of the boss 3 a which forms a sleeve aroundone end of the input shaft 2, and this oil line 91 is linked to an oilpressure control unit not illustrated. Therefore, simply by providingone set of seal rings 81 between the input shaft 2 and the boss 3 a, oilcommunication is established between the oil pressure control device andthe oil chamber of the hydraulic servo 12.

The operations of the automatic transmission 1 ₁₉ of the nineteenthembodiment will be now described with reference to FIG. 33, FIG. 34, andFIG. 35 below. As with the previously described embodiments, thevertical axes of the speed line diagram illustrated in FIG. 35 indicatethe speeds of the various rotary components, and the horizontal axisindicates the corresponding gear ratio of these rotary components. Inthe first planetary gear unit PU section of this speed line diagram, thevertical axis to the farthest horizontal edge (the right side of FIG.35) corresponds to sun gear S3, and moving to the left within thediagram, the vertical axes correspond to the ring gear R2, the carrierCR2, and the sun gear S2. Further, in the second planetary gear unit PRsection of this speed line diagram, the vertical axis to the farthesthorizontal edge (the right side of FIG. 35) corresponds to sun gear S1,and moving to the left within the diagram, the vertical axes correspondto the ring gear R1 and the carrier CR1. Further, the widths betweenthese vertical axes are inversely proportional to the number of teeth ofeach of the sun gears S1, S2, S3, and to the number of teeth of each ofthe ring gears R1, R3. Also, the horizontal dotted line in the diagramrepresents the rotation transmitted by the transmitting member 230.

As illustrated in FIG. 33, by engaging the clutch C1, the rotation ofthe input shaft 2 is input to the sun gear S1. Further, the carrier CR1is fixed to the case 3, and the ring gear R1 rotates at a reduced speedbased on the rotation of the input shaft 2 input into sun gear S1. Inother words, by engaging the clutch C1, the reduced speed rotation ofthe ring gear R1 is input to the sun gear S2 via the transmitting member230.

As illustrated in FIG. 34 and FIG. 35, within the second planetary gearunit PR, in first speed forward, second speed forward, third speedforward, and fourth speed forward, the rotation of the input shaft 2 isinput to the sun gear S1 by engagement of the clutch C1, the reducedspeed rotation is output to the ring gear R3 through the fixed carrierCR1, and the reduced speed rotation is input to the sun gear S3 via thetransmitting member 230. At this time, the ring gear R1 and the sun gearS3 rotate at a reduced speed, and therefore the transmitting member 230transmits a relatively large torque. On the other hand, in fifth speedforward, sixth speed forward, and first speed reverse, the rotation ofthe sun gear S3 is input to the ring gear R1 via the transmitting member230, and further, because the clutch C1 is released, as illustrated inFIG. 35, the sun gear S1 rotates based on the speed of ring gear R1 andthe fixation of the carrier CR1.

The other operations of the nineteenth embodiment are similar to thoseof the eighteenth embodiment (see FIG. 31 and FIG. 32), and accordinglydescription thereof will be omitted.

In the automatic transmission 1 ₁₉ of the nineteenth embodiment, due tothe second planetary gear unit PR and the clutch C3 being located on oneside of the first planetary gear unit PU, and the clutch C2 beinglocated on the axially opposite side of the first planetary gear unitPU, the planetary gear units PR and PU can be located more closelytogether, as compared to an embodiment wherein, for example, twoclutches C2 and C3 are located between the planetary gear units PR andPU, and the transmitting member 230 can be made relatively shorter. Bydoing so, the automatic transmission can be made more compact and morelightweight. Further, because the inertia (inertial force) can bereduced, the controllability of the automatic transmission can beincreased, and the occurrence of speed change shock can be reduced.Further, compared to the case wherein three clutches C1, C2, C3 arelocated on one side of the first planetary gear unit PU, the oil lines(for example, 2 a, 2 b, 91, 93, 94) that supply the hydraulic servos 11,12, and 13 of these clutches C1, C2, C3 can be more easily constructed,the manufacturing process can be simplified and the costs can bereduced.

Further, since the hydraulic servos 12, 13 are provided on the inputshaft 2, one set of seal rings 81 and 82 form a seal with the case 3 forsupply oil through the oil lines 2 a and 2 b within input shaft 2 to theoil chambers of hydraulic servos 12, 13, without providing the pairedseal rings between, for example, the input shaft 2 and the hydraulicservos 12, 13. Further, the hydraulic servo 11 can receive supply of oildirectly from the boss 3 b without passing through other components, andtherefore the oil supply can be connected by providing one set of sealrings 84. Therefore, oil can be supplied through sets of seal rings 81and 82, 84 for the hydraulic servos 11, 12, and 13, sliding resistancefrom the seal rings can be minimized, and therefore the efficiency ofthe automatic transmission can be improved.

Further, since the clutch C2 engages for first speed reverse, when thisclutch 2 is engaged in first speed reverse, the hub unit 224 thatconnects this clutch C2 and the sun gear S2 rotates at the same speed asthe input shaft 2, while the transmitting member 230 rotates in theopposite direction, and therefore the speed difference between thetransmitting member 230 and the hub unit 224 is large. However, sinceclutch C2 is located on the side of the first planetary gear unit PUopposite the second planetary gear unit PR, the transmitting member 230and the hub 224 can be spaced apart from one another. Compared to thecase wherein, for example, those parts come in contact in a multipleaxis construction, the loss of efficiency of the automatic transmissioncaused by the friction produced by the relative rotation between thoseparts can be avoided.

If the clutch C1 were to be placed between the ring gear R1 and the sungear S3, for example, the reduced speed rotation must be engaged anddisengaged, and a larger clutch C1 would be required. However, byplacing the clutch C1 between the input shaft 2 and the sun gear S1, theengaging and disengaging of the rotation of the input shaft 2 by thisclutch C1 indirectly engages and disengages the reduced speed rotationoutput from the ring gear R1 of the second planetary gear unit PR, theclutch C1 can be made more compact, and therefore the automatictransmission can be made more compact.

Further, because the automatic transmission 1 ₁₉ according to thenineteenth embodiment is directly coupled in fifth speed forward, infirst speed forward and fourth speed forward, the gear ratio can be moreprecisely set for optimum efficiency, and particularly when the vehicleis running at a high speed, the engine can be operated more efficientlyand fuel economy of the vehicle while running at a low to medium speedcan also be increased.

The transmitting member which links the planetary gear units PR and PUrequires rigidity to withstand the reduced speed torque that is input.In the case of a clutch that engages at a slow to medium speed and inthe case of a clutch that engages and disengages at reduced speed and islocated radially inward of the transmitting member, the clutch must havea large capacity and therefore a large diameter to provide the requiredcapacity. Therefore, in the event that the transmitting member passes onthe radially outer side of such a clutch, the diameter necessary for theclutch becomes even larger, the diameter of the transmitting member isenlarged more than necessary, and the automatic transmission as a wholehas a greater diameter. Therefore an object of the present embodiment isto avoid the need for enlargement of the diameter, and to provide a morecompact automatic transmission.

In this nineteenth embodiment, all clutches can be configured so as toavoid enlargement of the diameter of the transmitting member, becauseclutch C3 with a small capacity is provided radially inward of thetransmitting member 230.

Twentieth Embodiment

The twentieth embodiment, which is a partial modification of theeighteenth embodiment will now be described with reference to FIG. 36through FIG. 38. Components of the twentieth embodiment which are thesame as those of the eighteenth embodiment are denoted by the samereference numerals, and description thereof omitted, except for themodified features.

As FIG. 36 illustrates, the automatic transmission 1 ₂₀ of the twentiethembodiment comprises a brake B3 instead of a clutch C1, and enables thecarrier CR1 of the second planetary gear unit PR to be fixed by thebrake B3, and further differs from the eighteenth embodiment in theconstruction of the oil line for the hydraulic servo 12 of the secondplanetary gear unit PR.

Within this automatic transmission 1 ₂₀, the brake B3 is located on theside of the second planetary gear unit PR opposite (left side on thediagram) the first planetary gear unit PU. This brake B3 comprises ahydraulic servo 16, friction plates 76, and a hub unit 233.

The hub unit 233 of brake B3 is connected to the side plate on one sideof the carrier CR1, and this carrier CR1 is rotatably supported by theinput shaft 2 or the boss 3 a. The sun gear S1 is connected to the inputshaft 2. Ring gear R1 is connected to the sun gear S3 via transmittingmember 230.

The oil chamber of the hydraulic servo 12 is connected to an oil line 2a which is formed on the input shaft 2. This oil line 2 a, in turn, isconnected to the oil line 91 which is connected to an oil pressurecontrol unit not illustrated. Therefore, for hydraulic servo 11, simplyby providing one set of seal rings between the input shaft 2 and theboss unit 3 a of the case 3, the oil supply is connected from the oilpressure control device to the oil chamber of the hydraulic servo 12.

Operations of the automatic transmission 1 ₂₀ of the twentiethembodiment will now be described with reference to FIG. 36, FIG. 37, andFIG. 38. Now, as with the previously described embodiments, the verticalaxes of the speed line diagram illustrated in FIG. 38 indicate therespective speeds of the various rotary components, and the horizontalaxis represents the corresponding gear ratios of these rotarycomponents. In the first planetary gear unit PU section of this speedline diagram, the vertical axis to the farthest horizontal edge (theright side of FIG. 38) corresponds to sun gear S3 and, moving to theleft within the diagram, the vertical axes correspond to the ring gearR2, the carrier CR2, and the sun gear S2. Further, in the secondplanetary gear unit PR section of this speed line diagram, the verticalaxis to the farthest horizontal edge (the right side of FIG. 38)corresponds to sun gear S1 and, moving to the left within the diagram,the vertical axes correspond to the ring gear R1 and the carrier CR1.Further, the widths between these vertical axes are inverselyproportional to the number of teeth of each of the sun gears S1, S2, S3,and to the number of teeth of each of the ring gears R1, R3. Also, thehorizontal dotted line in the diagram represents the rotationtransmitted from the transmitting member 230.

As FIG. 36 illustrates, by engaging the brake B3, the carrier CR1 isfixed to the case 3. Further, the rotation of the input shaft 2 is inputto the sun gear S1, and the ring gear R1 rotates at a reduced speedbecause this carrier CR1 is fixed. In other words, by engaging the brakeB3, the reduced speed rotation of the ring gear R1 is input to the sungear S3 via the transmitting member 230.

In this manner, as FIG. 37 and FIG. 38 illustrate, in the secondplanetary gear unit PR, in first speed forward, second speed forward,third speed forward, and fourth speed forward, the rotation of the inputshaft 2 is input to the sun gear S1 by engaging the brake B3, thecarrier CR1 is fixed, the reduced speed rotation is output to the ringgear R3 by the rotation of the sun gear S1, and the reduced speedrotation is input to the sun gear S3 via the transmitting member 230. Inthis case, the ring gear R1 and the sun gear S3 are rotating at reducedspeed, and therefore the transmitting member 230 transmits a relativelylarge torque. On the other hand, in fifth speed forward, forward speedlevel, and first speed reverse, the rotation of the sun gear S3 is inputto the ring gear R1 via the transmitting member 230, and further,because the brake B3 is released, as FIG. 38 illustrates, the carrierCR1 rotates with the speed of ring gear R1 and the sun gear S1.

The operations of the second planetary gear unit are similar to those ofthe eighteenth embodiment, and accordingly description thereof will beomitted.

As described above, in the automatic transmission 1 ₂₀ of the twentiethembodiment, due to the second planetary gear unit PR and the clutch C3being located on one side of the first planetary gear unit PU, and theclutch C2 being located on the axially opposite side of the firstplanetary gear unit PU, the planetary gear units PR and PU can belocated more closely together, as compared to an embodiment wherein, forexample, two clutches C2 and C3 are located between the planetary gearunits PR and PU, and the transmitting member 230 for transmittingreduced speed rotation can be made relatively shorter. In this manner,the automatic transmission can be made more compact and morelightweight. Further, because the inertia (inertial force) can bereduced, the controllability of the automatic transmission can beincreased, and the occurrence of speed change shock can be reduced.

Further, since the hydraulic servos 11 and 12 are mounted on the inputshaft 2, one set of seal rings 81 and 82 serves to supply oil from theoil lines 2 a and 2 b provided within input shaft 2 to the oil chambersof hydraulic servos 12, 13 without providing seal rings between, forexample, the input shaft 2 and the hydraulic servos 12, 13. Therefore,oil can be supplied simply by providing one set of seal rings 81 and 82for each of the hydraulic servos 12, 13, sliding resistance from theseal rings can be minimized, and therefore the efficiency of theautomatic transmission can be improved.

Further, when the clutch C2 is engaged in first speed reverse, the hubunit 224 that connects this clutch C2 and the sun gear S2 rotates at thesame speed as the input shaft 2. Accordingly, by engaging clutch C2,while the transmitting member 230 is rotating in the opposite direction,will cause the speeds of the transmitting member 230 and the hub unit224 to become greatly different, but because clutch C2 is located on theside of the first planetary gear unit PU opposite the second planetarygear unit PR, the transmitting member 230 and the hub 224 can be spacedapart from one another. Compared to the case wherein, for example, thosecomponents come into contact in a multiple axis construction, thedecrease in efficiency of the automatic transmission caused by thefriction produced by the relative rotation between those components canbe avoided.

Further, since the output of the reduced speed rotation to the firstplanetary gear unit PU from the second planetary gear unit PR iscontrolled by engagement of the brake B3, the number of components (forexample drum-shaped members and so forth) can be reduced as compared toan embodiment wherein, for example, a clutch C1 is employed. Further,the brake B3 can receive a supply of oil directly from the case 3, andtherefore the configuration of the oil line can be simplified ascompared to the case wherein, for example, a clutch C1 is employed.

Further, the automatic transmission 1 ₂₀ according to the twentiethembodiment is directly coupled at fifth speed forward. Therefore, infirst speed forward and fourth speed forward, the gear ratio can be suchas to provide greater efficiency, and particularly when the vehicle isrunning at a high speed, the engine can be operated more efficiently,and fuel economy of the vehicle while running at a low to medium speedis increased.

In this embodiment also, the transmitting member which links theplanetary gear units PR and PU requires rigidity to withstand thereduced speed torque that is input. For example, in the case of a clutchthat engages at a slow to medium speed and a clutch that engages totransmit reduced speed rotation and that is located on the inner side ofthe transmitting member, the clutch must have a large capacity and,therefore, a large diameter to provide the necessary capacity.Therefore, in the event that the transmitting member passes on theradially outer side of such a clutch, even a larger diameter of theclutch becomes necessary, the diameter of the transmitting member isenlarged more than necessary, and the automatic transmission as a wholehas a greater diameter. Therefore an object of the present embodiment isto avoid enlargement of the diameter, and to provide a compact automatictransmission.

According to this twentieth embodiment, all clutches can be configuredwithout enlarging the diameter of the transmitting member, because aclutch C3 with a small capacity is provided on the inner side of thetransmitting member 230.

Twenty-first Embodiment

A twenty-first embodiment is a partial modification of the eighteenthembodiment and will now be described with reference to FIG. 39.Components of the twenty-first embodiment which are the same as those ofthe eighteenth embodiment are denoted by the same reference numerals,and description thereof will be omitted here, except for modifiedcomponents.

As FIG. 39 illustrates, the automatic transmission 1 ₂₁ of thetwenty-first embodiment differs from the eighteenth embodiment in theconfiguration of the clutch C1 and that of the second planetary gearunit PR. More specifically, in the diagram, the second planetary gearunit PR and the clutch C1 are on the right side of the planetary gearunit PU, and the counter gear 5 is located between the planetary gearunits PR and PU.

Within the automatic transmission 1 ₂₁ is a multi-disc clutch C1comprising a hydraulic servo 11, friction plates 71, a clutch drum 221,a hub unit 222 connected to a sun gear S3, and radially outward of theclutch C1 is a multi-disc clutch C2 comprising a hydraulic servo 12,friction plates 72, a clutch drum 223, and a hub unit 224. Further,radially outward of the hub 224 is a multi-disc brake B2 comprising ahydraulic servo 15 and friction plates 75.

The input shaft 2 is rotatably supported by the clutch drum 221, and afront edge portion of the inner circumferential surface of this drum 221is splined to the friction plates 71 of the clutch C1, which frictionplates 71 are intermeshed with the friction plates splined to the hubunit 222.

Further, the sun gear S1 is fixed to and supported by the boss 3 a, andthe carrier CR1 is connected to the input shaft 2 via a side plate. Thering gear 1 is rotatably supported by the boss 3 a, and also isconnected to the clutch drum 221. Further, the hub unit 222 is connectedto the sun gear S3 by transmitting member 230.

Now, the oil chamber of the hydraulic servo 11 is connected to the oilline 2 a which is formed on the input shaft 2 and is connected to theoil line 91 in the boss 3 a which, in turn, is connected to the oilpressure control device. This hydraulic servo 11 comprises one set ofseal rings 81 between the boss 3 b of the case 3 and the input shaft 2,and one set of seal rings 85 between the input shaft 2 and the clutchdrum 221. Thus, two sets of seal rings connect oil supply from the oilpressure control device to the oil chamber of the hydraulic servo 11.

At the other end of the input shaft 2 (left side in diagram) is amulti-disc clutch C that comprises a hydraulic servo 13, friction plates73, a clutch drum 225, and a hub unit 226. The friction plates 73 aresplined to a front edge portion of the inner surface of the clutch drum225 of this clutch C3, and friction plates 73 are intermeshed withfriction plates splined to the front edge of the outer circumferentialsurface of the hub unit 226, and this hub unit 226 is connected to theside plate of the carrier CR2.

The oil chamber of this hydraulic servo 13 is connected to an oil line 2b which is formed on the above-mentioned input shaft 2, and this oilline 2 b is connected to the oil line 93 of the boss 3 b, which boss 3 bforms a sleeve around one end of the input shaft 2. Therefore, an oilline from the oil pressure control unit, not illustrated, to the oilchamber of the hydraulic servo 13 is constructed simply by providing oneset of seal rings 82 between the boss 3 a of the case 3 and the clutchdrum 225.

On the radially outer side of the planetary gear unit PU is a multi-discbrake B1 comprising a hydraulic servo 14, friction plates 74, and a hubunit 228. The side plate of the carrier CR2 of the first planetary gearunit PU is connected to the hub unit 228 that is splined to frictionplates intermeshed with the friction plates 74 of the brake B1, andfurther, the hub unit 228 is connected to the inner race of the one-wayclutch F1. The sun gear S3 is meshed with the short pinion PS of thiscarrier CR2 and the long pinion PL of this carrier CR2 is meshed withthe sun gear S2 and the ring gear 2. One edge of this ring gear R2 isconnected to the counter gear 5 via the transmitting member 227.

The operations of the automatic transmission 1 ₂₁ differ from those ofthe eighteenth embodiment in that, within the second planetary gear unitPR, the carrier CR1 and the sun gear S1 have switched positions. Inother words, the sun gear S1 is fixed, and the rotation of the inputshaft 2 is input to the carrier CR1, but the other components are thesame as those of the eighteenth embodiment (see FIG. 31 and FIG. 32),and accordingly description will be omitted.

In the automatic transmission 1 ₂₁ of the twenty-first embodiment, dueto the second planetary gear unit PR and the clutch C2 being located onone side of the planetary gear unit PU, and the clutch C3 being locatedon the other axial side of the first planetary gear unit PU, theplanetary gear units PR and PU can be located more closely together, ascompared to an embodiment wherein, for example, two clutches C2 and C3are located between the planetary gear units PR and PU, and thetransmitting member 230 which transmits reduced speed rotation can bemade relatively shorter. By doing so, the automatic transmission can bemade more compact and more lightweight. Further, because the inertia(inertial force) can be reduced, the controllability of the automatictransmission can be increased, and the occurrence of speed change shockcan be reduced. Further, compared to the case wherein three clutches C1,C2, C3 are located on one side of the planetary gear unit PU, the oillines (for example, 2 a, 2 b, 91, 92, 93) that supply the hydraulicservos 11, 12, and 13 of these clutches C1, C2, C3 can be constructedeasily, the manufacturing process can be simplified, and the costs canbe reduced.

Further, since the counter gear 5 is located axially between theplanetary gear units PU and PR, the counter gear 5 can be located inapproximately the axial center of the automatic transmission. Forexample, when the automatic transmission is mounted on the vehicle, needfor enlargement in one direction (particularly in the rear directionwhen the side the drive source is the “front”) can be avoided becausethe counter gear 5 is mounted adjacent the drive wheel transmissiondevice. Because of this, particularly in the case of a FF vehicle,interference with the front wheels is reduced, and the mountability on avehicle can be improved such that the steering angle can be greatlyincreased, for example.

Further, the automatic transmission 1 ₂₁ is directly coupled in fifthspeed forward. Therefore, in first speed forward and fourth speedforward, the gear ratio can be specified for better efficiency, andparticularly when the vehicle is running at a high speed, the engine canbe operated more efficiently, and fuel economy is increased whilerunning at a low to medium speed.

Twenty-Second Embodiment

A twenty-second embodiment, which is a partial modification of thetwenty-first embodiment, will now be described with reference to FIG.40. FIG. 40 is a schematic cross-sectional diagram illustrating theautomatic transmission of the twenty-second embodiment. Components ofthe twenty-second embodiment which are the same as those of thetwenty-first embodiment are denoted by the same reference numerals, anddescription thereof omitted, except for modified components.

As FIG. 40 illustrates, the automatic transmission 1 ₂₂ of thetwenty-second embodiment differs from that of the twenty-firstembodiment in the configuration of the second planetary gear unit PR andthe clutch C2, and further differs in that brake B3 is utilized insteadof clutch C1, which enables the carrier CR1 of the second planetary gearunit PR to be fixed by the brake B3.

Within this automatic transmission 1 ₂₂, the brake B3 is located on theside (the right side of the diagram) of the second planetary gear unitPR opposite the planetary gear unit PU. This brake B3 comprises ahydraulic servo 16, friction plates 76, and a hub unit 233. Hub unit 233is connected to the sun gear S1 and is rotatably supported by the boss 3a. Further, the clutch C2 comprises a hydraulic servo 12, frictionplates 72, a drum member 223, and a hub unit 224 and is located on theouter side of the hub unit 233 of brake B3. The drum 223 of this clutchC2 is connected to one side plate of the carrier CR1, and the other sideplate of carrier CR1 is connected to the input shaft 2. Also, the ringgear R1 is connected to the sun gear S3 via transmitting member 230.

The oil chamber of the hydraulic servo 12 is linked to the oil line 91of the boss 3 a provided on the input shaft 2 in a sleeve form, via anoil hole (not illustrated) formed in the hub unit 233, and this oil line91 is linked to the oil pressure control device. This hydraulic servo 11comprises one set of seal rings 80 between the boss 3 a of the case 3and the hub unit 233, and one set of seal rings 86 between the hub unit233 and the drum 223. In other words, two sets of seal rings constructan oil line from the oil pressure control device to the oil chamber ofthe hydraulic servo 12.

The automatic transmission 1 ₂₂, of this twenty-second embodimentdiffers from that of the twentieth embodiment in that, within the secondplanetary gear unit PR, the carrier CR1 and the sun gear S1 haveswitched positions; in other words, the sun gear S1 is fixed by thebrake B3, and the rotation of the input shaft 2 is input to the carrierCR1, but the other components are the same as those of the twentiethembodiment (see FIG. 37 and FIG. 38), and accordingly descriptionthereof will be omitted.

In the automatic transmission 1 ₂₂ of the twenty-second embodiment, dueto the second planetary gear unit PR and the clutch C2 being located onone side of the planetary gear unit PU, and the clutch C3 being locatedon the axially opposite side of the first planetary gear unit PU, theplanetary gear units PR and PU can be located more closely together, ascompared with an embodiment wherein, for example, two clutches C2 and C3are located between the second planetary gear units PR and PU, and thetransmitting member 230 for transmitting reduced speed rotation can bemade relatively shorter. By doing so, the automatic transmission can bemade more compact and more lightweight. Further, because the inertia(inertial force) can be reduced, the controllability of the automatictransmission can be increased, and the occurrence of speed change shockcan be reduced.

Further, since the counter gear 5 is located between the first planetarygear unit PU and the second planetary gear unit PR, the counter gear 5can be located in approximately the axial center of the automatictransmission. For example, when the automatic transmission is mounted onthe vehicle, enlargement in one direction (particularly in the reardirection when the side facing the drive source is the “front”) can beprevented because the counter gear 5 is mounted adjacent the drive wheeltransmission device. Because of this, particularly in the case of a FFvehicle, interference with the front wheels is reduced, mountability ona vehicle is improved, and the steering angle is greatly increased.

Further, since the reduced speed rotation output to the first planetarygear unit PU from the second planetary gear unit PR is engaged anddisengaged by the brake B3, the number of components (for exampledrum-shaped members and so forth) can be reduced as compared to the casewherein, for example, a clutch C1 is provided. Further, the brake B3 canconnect with an oil line directly from the case 3, and therefore theconfiguration of the oil line can be simplified as compared to the casewherein, for example, a clutch C1 is provided.

Further, the automatic transmission 1 ₂₂ according to the presentembodiment is directly coupled in fifth speed forward. Therefore, infirst speed forward and fourth speed forward, the gear ratio can bebetter set for maximum efficiency, and particularly when the vehicle isrunning at a high speed, the engine can be operated more efficiently,and fuel economy while running at a low to medium speed can be improved.

If a clutch is located between the planetary gear units PR and PU forexample, the length of the transmitting member that links the planetarygear units PR and PU becomes axially longer, and since this linkingmember transmits the reduced speed rotation, the thickness of the membermust be increased so as to withstand the high torque, and therefore theweight also increases. Therefore, an object of the present invention isto provide an automatic transmission that can shorten the distancebetween the speed reduction (second) planetary gear unit PR and thefirst planetary gear unit PU, and avoid increase in weight.

In this twenty-second embodiment the clutch C2 is disposed on the sideof the second planetary gear unit PR axially opposite the firstplanetary gear unit PU, and, therefore, a clutch between the planetarygear units PR and PU is not necessary, and the length of thetransmitting member 230 can be made that much shorter. Therefore,increase in weight of the automatic transmission as a whole can beavoided.

Twenty-third Embodiment

A twenty-third embodiment, which is a partial modification of theeighteenth embodiment will now be described, with reference to FIG. 41.Components of the twenty-third embodiment which are the same as those ofthe eighteenth embodiment are denoted by the same reference numerals,and description thereof omitted, except for modified components.

As FIG. 41 illustrates, the automatic transmission 1 ₂₃ of thetwenty-third embodiment differs from the eighteenth embodiment in theconfiguration of the clutch C1 and the second planetary gear unit PR.More specifically, the second planetary gear unit PR and the clutch C1are located on one side (the right side in the diagram) of the firstplanetary gear unit PU, and the counter gear 5 is located between theplanetary gear units PR and PU. The twenty-third embodiment also differsin that the locations of the clutch C2 and the brake B2 are switched ascompared to the automatic transmission 1 ₁₈ of the eighteenth embodiment(see FIG. 30).

Within the automatic transmission 1 ₂₃, mounted on the input shaft 2 isa multi-disc clutch C3 comprising a hydraulic servo 13, friction plates73, a clutch drum 225, a hub unit 226 connected to sun gear S2, and,located radially outward of clutch C3, is a multi-disc clutch C1comprising a hydraulic servo 11, friction plates 71, a clutch drum 221and a hub unit 224.

The oil chamber of the hydraulic servo 13 is connected to the oil line 2a formed on the input shaft 2, and this oil line 2 a is connected to theoil line 91 of the boss 3 a, which oil line 91, in turn, is connected tothe oil pressure controller not illustrated. Thus, because the hydraulicservo 13 is mounted on the input shaft 2, simply providing one set ofseal rings 81 between the boss 3 a and the input shaft 2 serves toconnect oil supply from the oil pressure controller to the oil chamberof the hydraulic servo 13.

Further, the oil chamber of the hydraulic servo 11 is connected to theoil line 92 of the boss 3 a, which oil line 92, in turn, is connected tothe oil pressure controller. Thus, for the hydraulic servo 11, simply byproviding one set of seal rings 80 between the boss 3 a and the clutchdrum 221, oil supply from the oil pressure controller is connected tothe oil chamber of the hydraulic servo 11.

The input shaft 2 is connected to the clutch drum 225 of the clutch C3,and the front portion of the inner surface of this clutch drum 225 issplined with the friction plates 73. Friction plates 73 are intermeshedwith friction plates splined to the hub unit 226, and hub unit 226 isconnected to the sun gear S2.

The input shaft 2 rotatably supports the clutch drum 221. The innersurface of this clutch drum 221 is splined to the friction plates 71 ofthe clutch C1 which is operated by the hydraulic servo 11, and thesefriction plates 71 are intermeshed with friction plates splined to thehub unit 222 that is connected to the ring gear R1. Ring gear R1 isrotatably supported by the boss 3 a via hub unit 222. The sun gear S1 isconnected to the input shaft 2, and the carrier CR1 is fixed to andsupported by the boss 3 a via a side plate. Also, the clutch drum 221 isconnected to the sun gear S3 via the transmitting member 230.

The boss 3 b of the case 3 is in the form of a sleeve fitted on one endof the input shaft 2, and extending as a sleeve on the opposite end ofinput shaft 2 is a boss 3 a, which supports a multi-disc clutch C1comprising a hydraulic servo 12, friction plates 72, a clutch drum 223,and a hub unit 224. The oil chamber of this hydraulic servo 12 isconnected to oil line 93 of the boss 3 b, which oil line 93, in turn, isconnected to the oil pressure controller. In other words, theabove-mentioned hydraulic servo 12 is connected to the oil pressurecontroller by one set of seal rings 84 between the boss 3 b and theclutch drum 223.

A front portion of the inner surface of the clutch drum 223 is splinedto friction plates 72 which are intermeshed with friction plates splinedto a front portion of the outer surface of the hub unit 224. Further,radially outward of the clutch C2 is a multi-disc brake comprising anhydraulic servo 15 and friction plates 75, and the outer circumferentialsurface of hub unit 224 is splined to friction plates 75 that can beengaged by operation of the hydraulic servo 15. Also, this hub unit 224is connected to the sun gear S2.

Radially outward of the planetary gear unit PU is a multi-disc brake B1comprising a hydraulic servo 14, friction plates 74, and a hub unit 228.The side plate of the carrier CR2 of the first planetary gear unit PU isconnected to the hub unit 228 that is splined to the friction plates ofthe above-mentioned brake B1, and further, the hub unit 228 is connectedto the inner race of the one-way clutch F1. The sun gear S3 is meshedwith the short pinion PS of this carrier CR2. The long pinion PL of thiscarrier CR2 meshes with the sun gear S2 and the ring gear R2, and to oneedge of this ring gear R2 is connected the transmitting member 227, andring gear R2 is linked to the counter gear 5 via this transmittingmember 227.

The operations of the automatic transmission 1 ₂₃, of this twenty-thirdembodiment are similar to those of the eighteenth embodiment (see FIG.31 and FIG. 32), and, accordingly, description thereof will not berepeated here.

In the automatic transmission 1 ₂₃ of this embodiment, due to the secondplanetary gear unit PR and the clutch C3 being located on one side ofthe first planetary gear unit PU, and the clutch C2 being located on theaxially opposite side of the first planetary gear unit PU, the planetarygear units PR and PU can be located more closely together, as comparedto the case wherein, for example, two clutches C2 and C3 are locatedbetween the planetary gear units PR and PU, and the transmitting member230 for transmitting reduced speed rotation can be relatively shorter.By doing so, the automatic transmission can be made more compact andmore lightweight. Further, because the inertia (inertial force) can bereduced, the controllability of the automatic transmission can beincreased, and the occurrence of speed change shock can be reduced.Further, compared to the case wherein three clutches C1, C2, C3 arelocated on one side of the first planetary gear unit PU, the oil lines(for example, 2 a, 91, 92, 93) that supply the hydraulic servos 11, 12,and 13 of these clutches C1, C2, C3 can be more easily constructed, themanufacturing process can be simplified and the costs can be reduced.

Further, since the hydraulic servo 13 is mounted on the input shaft 2,one set of seal rings 81 serves to connect the oil supply to the oillines 2 a provided within input shaft 2, and therefore oil can besupplied to the oil chamber of hydraulic servo 13 without providing sealrings between, for example, the input shaft 2 and the hydraulic servo12. Further, the hydraulic servos 11 and 12 can receive supply of oildirectly from the bosses 3 a, 3 b extending from the case 3, withoutpassing through other components. Therefore, oil can be supplied simplyby providing one set of seal rings 81, 80, 84 for each of the hydraulicservos 11, 12, and 13, sliding resistance from the seal rings can beminimized, and therefore the efficiency of the automatic transmissioncan be improved.

Further, because the clutch C3 is located radially inward of the clutchC1, the clutch C1, which must transmit a relatively large torque inorder to transmit the reduced speed rotation, can be located on theouter circumference side, and its hydraulic servo 11 can have anincreased diameter. Thus, the pressure-receiving area of the oil chamberof the hydraulic servo 11 can be enlarged, and the torque transmittingcapacity of this clutch C1 can be increased. By configuring the clutchC3 to have a smaller torque transmitting capacity than clutch C1, theautomatic transmission can be made more compact.

Because when clutch C2 is engaged in first speed reverse, thetransmitting member 230 rotates in the opposite direction while the hubunit 224 that connects clutch C2 and the sun gear S2 rotates in the samedirection as the input shaft 2, the transmitting member 230 and the hubunit 224 rotate at greatly different speeds, but because this clutch C2is located on the side of the first planetary gear unit PU opposite thesecond planetary gear unit PR, the transmitting member 230 and the hubhunt 224 can be spaced apart from one another. Compared to the casewherein, for example, these components come into contact in a multipleaxis construction, the decrease in efficiency of the automatictransmission caused by the friction produced by the relative rotationbetween these components can be avoided.

Further, because the counter gear 5 is located between the planetarygear units PU and PR, the counter gear 5 can be located in approximatelythe axial center of the automatic transmission. For example, enlargementof the automatic transmission toward the rear of the vehicle (when theinput side facing the drive source is the “front”) is not necessarybecause the counter gear 5 is mounted adjacent the drive wheeltransmission device. Because of this, particularly in the case of a FFvehicle, interference with the front wheels is reduced, the mountabilityon a vehicle is improved, and the steering angle can be greatlyincreased.

Further, the automatic transmission 1 ₂₃ according to the presentembodiment is directly coupled in fifth speed forward. Therefore, infirst speed forward and fourth speed forward, the gear ratio can bedetermined for greater efficiency, when the vehicle is running at a highspeed the engine can be operated more efficiently, and fuel economy ofthe vehicle can be increased when running at a low to medium speed.

The transmitting member for linking the planetary gear units PR and PUrequires rigidity to withstand the reduced speed torque that is input.For example, a clutch that engages at a slow to medium speed and aclutch that engages and disengages reduced speed rotation and that islocated radially inward of the linking member must have a largecapacity, and therefore must have a diameter corresponding to thisrequired large capacity. Therefore, in the event that the transmittingmember passes radially outward of such a clutch, an even larger diameterfor the clutch becomes necessary, the diameter of the transmittingmember must be further enlarged, and the diameter of the automatictransmission as a whole becomes greater. Therefore an object of thepresent embodiment is to reduce the diameter, and to provide a morecompact automatic transmission.

According to the present embodiment, all clutches can be designed toavoid enlarging the diameter of the transmitting member, by designingclutch C3 to have a small capacity and to be located radially inward ofthe transmitting member 230.

Twenty-fourth Embodiment

The twenty-fourth embodiment is a partial modification of thetwenty-third embodiment and will be described with reference to FIG. 42.Components of the twenty-fourth embodiment which are the same as thoseof the twenty-third embodiment are denoted by the same referencenumerals, and description thereof will not be repeated here, except formodified components.

As FIG. 42 illustrates, the automatic transmission 1 ₂₄ of thetwenty-third embodiment is modified with respect to the configuration ofthe clutch C1, as compared to that of the automatic transmission 1 ₂₃ ofthe eighteenth embodiment (see FIG. 41).

Within the automatic transmission 1 ₂₄, the clutch C1 is located on theside of the second planetary gear unit PR opposite (right side on thediagram) the first planetary gear unit PU. A front portion of the innercircumferential surface of the drum 221, which is connected to the inputshaft 2, is splined to friction plates 71 which are intermeshed withfriction plates splined to the hub unit 222. The hub unit 222 isconnected to the sun gear S1 of the second planetary gear unit PR.

The side plate of the carrier CR1 of the second planetary gear unit PRis fixed to and supported by the case 3. The ring gear R1 is connectedto the sun gear S3 by the transmitting member 230. The clutch C3comprises a hydraulic servo 13, friction plates 73, a drum 225, and ahub unit 226 and is located radially inward of the transmitting member230, that is to say, enclosed within transmitting member 230.

The operations of the automatic transmission 1 ₂₄, are the same as thoseof the nineteenth embodiment (see FIG. 34 and FIG. 35), and,accordingly, description thereof will not be repeated here.

In the automatic transmission 1 ₂₄, because the second planetary gearunit PR and the clutch C3 are located on one side of the first planetarygear unit PU, and the clutch C2 is located on the other (axiallyopposite) side of the first planetary gear unit PU, the planetary gearunits PR and PU can be located more closely together, as compared to thecase wherein, for example, two clutches C2 and C3 are located betweenthe planetary gear units PR and PU, and the transmitting member 230 fortransmitting the reduced speed rotation can be relatively shorter. Bydoing so, the automatic transmission can be made more compact and morelightweight. Further, because the inertia (inertial force) can bereduced, the controllability of the automatic transmission can beincreased, and the occurrence of speed change shock can be reduced.Further, compared to the case wherein three clutches C1, C2, C3 arelocated on one side of the planetary gear unit PU, the oil lines (forexample, 2 a, 91, 92, 93) that supply the hydraulic servos 11, 12, and13 of these clutches C1, C2, C3 can be more easily constructed, themanufacturing process can be simplified and the costs can be reduced.

Further, because the hydraulic servo 13 is mounted on the input shaft 2,one set of seal rings 81 seal the case 3 with the oil lines 2 a providedwithin input shaft 2 to supply oil to the oil chamber of hydraulic servo13 without providing seal rings between, for example, the input shaft 2and the hydraulic servo 13. Further, the hydraulic servos 11 and 12 canreceive supply of oil directly from the bosses 3 a, 3 b extending fromthe case 3, without passing through other components, and therefore theoil supply can be connected by providing one set of seal rings 80, 84.Therefore, oil can be supplied simply by providing one set of seal rings81, 80, 84 for each of the hydraulic servos 11, 12, and 13, slidingresistance from the seal rings can be minimized, and therefore theefficiency of the automatic transmission can be improved.

Further, when the clutch C2 is engaged in first speed reverse, thetransmitting member 230 rotates in the opposite direction while the hubunit 224 that connects this clutch C2 and the sun gear S2 rotates in thesame direction as the input shaft 2. Accordingly, the transmittingmember 230 and the hub unit 224 rotate at greatly different speeds.However, because this clutch C2 is located on the side of the firstplanetary gear unit PU opposite the second planetary gear unit PR, thetransmitting member 230 and the hub unit 224 can be spaced apart fromone another. Compared to the case wherein, for example, those componentscome into contact in a multiple axis construction, a decrease inefficiency of the automatic transmission caused by the friction producedby the relative rotation between those components can be avoided.

Further, because the counter gear 5 is located axially between theplanetary gear units PU and PR, the counter gear 5 can be located inapproximately the axial center of the automatic transmission. Forexample, when the automatic transmission is mounted on a vehicle,enlargement towards the rear (when the input side facing the drivesource is the “front”) is not necessary because the counter gear 5 ismounted to mate with the drive wheel transmission device. Because ofthis, particularly in the case of a FF vehicle, interference with thefront wheels is reduced, the mountability on a vehicle is improved, andthe steering angle can be greatly increased.

If the clutch C1 were to be placed between the ring gear RI and the sungear S3 for example, it would be required to engage and disengage lowspeed and high torque rotation, and to be relatively large, but byplacing the clutch C1 between the input shaft 2 and the sun gear S1, theengaging and disengaging of the rotation of the input shaft 2 by clutchC1 indirectly engages and disengages reduced speed rotation output fromthe ring gear R1 of the second planetary gear unit PR, the clutch C1 canbe made more compact, and therefore the automatic transmission can bemade more compact.

Further, the automatic transmission 1 ₂₄ according to the presentembodiment is directly coupled in fifth speed forward. Therefore, infirst speed forward and fourth speed forward, the gear ratio can be moreprecisely set to improve efficiency and when the vehicle is running at ahigh speed, the engine can be operated more efficiently, and better fueleconomy is achieved while running at a low to medium speed.

In this embodiment also, the transmitting member linking the planetarygear units PR and PU requires rigidity to withstand the reduced speedtorque that is input. For example, a clutch that engages at a slow tomedium speed and a clutch that engages and disengages reduced speedrotation and that is located on the radially inner side of thetransmitting member must have a large capacity and, therefore, adiameter appropriate for such a large capacity becomes necessary.Therefore, in the event that the transmitting member passes on theradially outer side of this type of clutch, an even larger diameter forthe clutch becomes necessary, the diameter of the transmitting member isenlarged more than necessary, and the diameter of the automatictransmission as a whole is increased. Therefore, an object of thepresent embodiment is to reduce the diameter and to provide a morecompact automatic transmission.

According to the present embodiment, all clutches can be configured toavoid enlarging the diameter of the transmitting member, by locating aclutch C3 with a small capacity on the radially inner side of thetransmitting member 230.

Twenty-fifth Embodiment

A twenty-fifth embodiment, which is a partial modification of thetwenty-third embodiment will now be described with reference to FIG. 43.Components of the twenty-fifth embodiment which are the same as those ofthe twenty-third embodiment are denoted by the same reference numerals,and description thereof will not be repeated here.

As FIG. 43 illustrates, the automatic transmission 1 ₂₅ of thetwenty-third embodiment utilizes a brake B3 instead of the clutch C3,and has the carrier CR1 of the second planetary gear unit PR capable ofbeing fixed by the brake B3, in which respect it differs from theautomatic transmission 1 ₂₃ of the twenty-third embodiment (see FIG.41).

In this automatic transmission 1 ₂₅, the brake B3 is located on the side(the right side of the diagram) of the second planetary gear unit PRopposite the planetary gear unit PU. This brake B3 comprises a hydraulicservo 16, friction plates 76, and a hub unit 233. The hub unit 233 ofthis brake B3 is connected to the carrier CR1, and this carrier CR1 isrotatably supported by the input shaft 2. Further, the sun gear S1 isconnected to the input shaft 2. Also, the ring gear R1 is connected tothe sun gear S3, via transmitting member 230. The clutch C3, whichcomprises a hydraulic servo 13, friction plates 73, a drum 225, and ahub unit 226, is located on the radially inner side of the transmittingmember 230, that is to say, is enclosed within transmitting member 230.

The operations of the automatic transmission 1 ₂₅ are the same as thoseof the twentieth embodiment (see FIG. 37 and FIG. 38), and accordinglydescription thereof will not be repeated here.

In the automatic transmission 1 ₂₅ of this twenty-fifth embodiment,since the second planetary gear unit PR and the clutch C3 are located onone axial side of the first planetary gear unit PU, and the clutch C2 islocated on the other axial side of the first planetary gear unit PU, theplanetary gear units PR and PU can be located more closely together, ascompared to the case wherein, for example, two clutches C2 and C3 arelocated between the planetary gear units PR and PU, and the transmittingmember 230 for transmitting the reduced speed rotation can be relativelyshorter. In this manner, the automatic transmission can be made morecompact and more lightweight. Further, because the inertia (inertialforce) can be reduced, the controllability of the automatic transmissioncan be increased, and the occurrence of speed change shock can bereduced.

Further, since the hydraulic servo 13 is mounted on the input shaft 2,one set of seal rings 81 serves to seal the case 3 to the oil lines 2 aprovided within input shaft 2, and therefore oil can be supplied to theoil chamber of hydraulic servo 13 without providing seal rings between,for example, the input shaft 2 and the hydraulic servo 12. Further, thehydraulic servo 12 can receive supply of oil from the boss 3 b extendingfrom the case 3, without passing through other components and supply ofoil is secured by providing one set of seal rings 84. Therefore, oil canbe supplied simply by providing one set of seal rings 81, 84 for each ofthe hydraulic servos 12, 13, sliding resistance from the seal rings canbe minimized, and therefore the efficiency of the automatic transmissioncan be improved.

Further, when clutch C2 is engaged in first speed reverse, thetransmitting member 230 rotates in the opposite direction while the hubunit 224 that connects this clutch C2 and the sun gear S2 rotates in thesame direction as the input shaft 2, and the difference in speedsbetween the transmitting member 230 and the hub unit 224 will be great;however because this clutch C2 is located on the side of the firstplanetary gear unit PU opposite the second planetary gear unit PR, thetransmitting member 230 and the hub hunt 224 can be spaced apart fromone another. Compared to the case wherein, for example, these componentscome in contact in to a multiple axis construction, the decrease inefficiency of the automatic transmission caused by the friction producedby the relative rotation between those components can be avoided.

Further, since the counter gear 5 is located axially intermediate theplanetary gear units PU and PR, the counter gear 5 can be located inapproximately the axial center of the automatic transmission. Again inthis embodiment, there is no need for enlargement towards the rear (whenthe input side facing the drive source is the “front”) because thecounter gear 5 is mounted to mate with the drive wheel transmissiondevice. Thus, particularly in the case of a FF vehicle, interferencewith the front wheels is reduced, mountability on a vehicle is improved,and the steering angle can be greatly increased.

Further, since the reduced speed rotation output to the first planetarygear unit PU from the second planetary gear unit PR is engaged anddisengaged by the brake B3, the number of components (for exampledrum-shaped members and so forth) can be reduced as compared to the casewherein, for example, a clutch C1 is provided. Further, the brake B3 canbe directly connected with an oil line in the case 3, and therefore theconfiguration of the oil line can be simplified as compared to the casewherein, for example, a clutch C1 is used.

Further, the automatic transmission 1 ₂₅ according to the twenty-fifthembodiment is directly coupled in fifth speed forward. Therefore, infirst speed forward and fourth speed forward, the gear ratio can bebetter set for efficiency, and particularly when the vehicle is runningat a high speed, the engine can be operated more efficiently, and fueleconomy can be increased in running at a low to medium speed.

In this embodiment also, the transmitting member linking the planetarygear units PR and PU requires rigidity to withstand the reduced speedtorque that is input. Further, in the case of a clutch that engages at aslow to medium speed and a clutch that engages and disengages reducedspeed rotation and that is located on the radially inner side of thetransmitting member, the clutch must have a large capacity and thereforea large diameter to provide the required torque transmitting capacity.Therefore, in the event that the transmitting member is the type thatpasses on the radially outward side of this type of clutch, an evenlarger diameter becomes necessary, the diameter of the transmittingmember must be further enlarged, and the automatic transmission as awhole must have a greater diameter. Therefore, an object of the presentembodiment is to avoid enlargement of the diameter, and to provide amore compact automatic transmission.

In this twenty-fifth embodiment, all clutches can be accommodatedwithout enlarging the diameter of the linking member, because clutch C3with a small capacity is located radially inward of the transmittingmember 230.

While the above first through twenty-fifth embodiments of the presentinvention were described as being applicable to an automatictransmission having a torque converter, the invention is not so limited,and any motion-starting device may be used that would transmit thetorque (rotation) at start of movement. Further, while the foregoingembodiments have been described as mounted on a vehicle having an engineas a drive source, the invention is not so limited, and any drive sourcemay be used as a matter of course, and the present invention may beapplied to a hybrid vehicle. Further, the above-described automatictransmission is favorable for use in a FF vehicle, but is not so limitedto this, and can be used in a FR vehicle, a four-wheel drive vehicle, orvehicles with other types of drive systems.

Further, the above first through twenty-fifth embodiments have beendescribed as having a double pinion planetary gear unit as the secondplanetary gear unit PR, i.e. as a reduced speed rotation output means,but again the invention is not so limited, and a single pinion planetarygear unit may also be used.

Further, the above first through twentieth embodiments and thetwenty-third through twenty-fifth embodiments have been described ashaving input of the rotation of the input shaft 2 into the sun gear S1of second planetary gear unit PR, with fixing the rotation of thecarrier CR1, whereby the ring gear R1 rotates at a reduced speed.However, the rotation of the sun gear S1 may be fixed, with the rotationof the input shaft 2 input to the carrier CR such that the ring gear R1rotates at a reduced speed.

Further, the first embodiment and the second embodiment have beendescribed with the input side and the output side of the automatictransmission interchanged. Likewise, the input side and the output sidemay be interchanged for the automatic transmission according to theother embodiments.

As described above, the automatic transmission according to the presentinvention is used to advantage on vehicles such as automobiles, trucks,busses, and so forth, and is particularly suitable for use with vehicleswhich require reduction in size and reduction in weight and furtherrequire reduction in shock upon changing speeds.

1. An automatic transmission comprising: an input shaft rotatably drivenby a drive source; a first planetary gear unit comprised of first,second, third, and fourth rotary components; reduced speed rotationoutput means for outputting rotation at a reduced speed to said firstrotary component; a first clutch that connects and disconnects saidinput shaft and said second rotary component; a second clutch thatconnects and disconnects said input shaft and said third rotarycomponent; an output member that outputs the rotation of said fourthrotary component to a drive wheel transmission mechanism; wherein saidreduced speed rotation output means and said first clutch are located onone axial side of said first planetary gear unit; and wherein saidsecond clutch is located on a second axial side of said first planetarygear unit, opposite said first axial side.
 2. An automatic transmissionaccording to claim 1, further comprising a transmitting member linkingsaid reduced speed rotation output means to said first planetary gearunit; and wherein said first clutch is located radially inward of saidtransmitting member.
 3. An automatic transmission according to claim 2wherein said reduced speed rotation output means is a speed reducingsecond planetary gear unit comprising an input rotary element forreceiving input of rotation of said input shaft, a reduced speed rotaryelement that rotates at a speed reduced from the speed of rotation ofthe input rotary element, a fixed element, and a third clutch forcontrolling the connection, through said transmitting member, betweensaid reduced speed rotary element and said first rotary component;wherein said reduced speed rotation is transmitted to said first rotarycomponent by engagement of said third clutch.
 4. An automatictransmission according to claim 3 wherein said fixed element is a fixedcarrier having pinions meshed with said input rotary element and saidreduced speed rotary element.
 5. An automatic transmission according toclaim 1 wherein said reduced speed rotation output means is a speedreducing second planetary gear unit comprising an input rotary componentfor receiving input of rotation of said input shaft, a reduced speedrotary component that rotates at a speed reduced from the speed ofrotation of the input rotary component, a fixed component, and a thirdclutch for controlling the connection, through said transmitting member,between said reduced speed rotary component and said first rotarycomponent; wherein said reduced speed rotation is transmitted to saidfirst rotary component by engagement of said third clutch.
 6. Anautomatic transmission according to claim 5, wherein said first clutchis located radially inward of said third clutch.
 7. An automatictransmission according to claim 6, wherein: said third clutch comprisesfriction members and a drum unit and a hub unit that are linked uponengagement of said friction members, wherein: said hub unit is linked tosaid reduced speed rotary component; said drum unit forms a hydraulicservo with a piston sealed in an oil-tight manner, and is linked to saidfirst rotary component; and said first clutch is located radially inwardof said drum unit.
 8. An automatic transmission according to claim 7,wherein: friction members of said third clutch are located radiallyoutward of said second planetary gear unit; and wherein a hydraulicservo of said third clutch is disposed adjoining said second planetarygear unit on said one axial side of said first planetary gear unit. 9.An automatic transmission according to claim 8, wherein a hydraulicservo of a first brake, for holding against rotation said first rotarycomponent of said first planetary gear unit to which reduced speedrotation is input, is located radially outward of the hydraulic servo ofsaid third clutch.
 10. An automatic transmission according to claim 5wherein: an engagement element of said second planetary gear unit isfixed to a first boss extending from one wall of a case; a hydraulicservo of said third clutch is mounted on said first boss unit; ahydraulic servo of said second clutch is mounted on a second boss thatextends from another wall of said case; said first clutch is locatedadjoining said first planetary gear unit and comprises friction members,a hydraulic servo, a drum unit, and a hub unit integral with saidhydraulic servo; and said drum unit is linked to said input shaft. 11.An automatic transmission according to claim 10, further comprising: atransmitting member linking said first and second planetary gear units;and wherein said third clutch is disposed radially inward of saidtransmitting member.
 12. An automatic transmission according to claim11, wherein said first clutch and said third clutch are located axiallyadjacent and radially inward of said transmitting member.
 13. Anautomatic transmission according to claim 12, wherein: said third clutchcomprises friction members, a drum unit, and a hydraulic servo; whereinsaid hydraulic servo is located on the side of said friction membersaxially opposite said second planetary gear unit; and said drum unitserves as a cylinder of said hydraulic servo and is linked to said inputshaft.
 14. An automatic transmission according to claim 13, wherein thehydraulic servo of said third clutch is located adjoining the hydraulicservo of said first clutch, between the hydraulic servo of said firstclutch and the friction members of said third clutch.
 15. An automatictransmission according to claim 5 wherein said fixed element is a fixedcarrier having pinions meshed with said input rotary element and saidreduced speed rotary element.
 16. An automatic transmission according toclaim 1, wherein said reduced speed rotation output means is a speedreducing second planetary gear unit comprising an input rotary elementfor receiving input of rotation of said input shaft, a reduced speedrotary element that is linked to said first rotary component at alltimes and rotates at said reduced speed, a fixable element, a thirdclutch for selectively connecting said input shaft and said input rotarycomponent, and a third brake for fixing said fixable element; whereinsaid reduced rotation is transmitted to said first rotary component byengagement of said third clutch and said third brake.
 17. An automatictransmission according to claim 16, further comprising: a transmittingmember linking said reduced speed rotation output means and said firstplanetary gear unit; and wherein said third brake is located on the sideof said second planetary gear unit axially opposite said first planetarygear unit.
 18. An automatic transmission according to claim 17, whereinsaid third brake comprises a hydraulic servo including a cylinder formedin a case housing said automatic transmission.
 19. An automatictransmission according to claim 17 wherein: said third clutch comprisesfriction members, a drum unit, and a hydraulic servo; said hydraulicservo is located on the side of said friction members axially oppositesaid second planetary gear unit; and; said drum unit serves as acylinder of said hydraulic servo and is linked to said input shaft. 20.An automatic transmission according to claim 16 wherein said fixableelement is a carrier having pinions meshed with said input rotaryelement and said reduced speed rotary element.
 21. An automatictransmission according to claim 1, wherein said reduced speed rotationoutput means is a second planetary gear unit comprising an input rotaryelement for receiving input of rotation of said input shaft, a reducedspeed rotary element that rotates at a speed reduced from the speed ofrotation of the input rotary element and is connected to said firstrotary component at all times, a fixable rotary element, and a thirdbrake for fixing said fixable rotary element against rotation; whereinsaid reduced speed rotation is transmitted to said first rotarycomponent by engagement of said third brake.
 22. An automatictransmission according to claim 21, wherein said third brake is locatedon the side of said second planetary gear unit axially opposite saidfirst planetary gear unit; and wherein the hydraulic servo of said thirdbrake comprises a hydraulic servo including a cylinder formed in a casehousing said automatic transmission.
 23. An automatic transmissionaccording to claim 21 wherein said fixable element is a carrier havingpinions meshed with said input rotary element and said reduced speedrotary element.
 24. An automatic transmission according to claim 1providing six forward speeds and one reverse speed, and wherein infourth forward speed said first clutch and said second clutch areengaged.
 25. An automatic transmission according to claim 24, whereinsaid first planetary gear unit is a multiple type planetary gear unit,comprising a first sun gear, a long pinion which meshes with said firstsun gear, a short pinion which meshes with said long pinion, a carrierrotatably supporting said long pinion and said short pinion, a secondsun gear meshing with said short pinion, and a ring gear meshing withsaid long pinion; wherein said first rotary component is said first sungear which is fixed by engagement of said first brake; wherein saidsecond rotary component is said second sun gear to which rotation ofsaid input shaft is input by engagement of said first clutch; whereinsaid third rotary component is said carrier which receives input ofrotation of said input shaft by engagement of said second clutch, andwhich is fixed by engagement of said second brake; and and wherein saidfourth rotary component is said ring gear linked to said output member.26. An automatic transmission according to claim 25, wherein, in firstspeed forward, said first clutch and said second brake are engaged;wherein, in second speed forward, said first clutch and said first brakeare engaged; wherein, in third speed forward, reduced speed rotation isinput to said first rotary component from said reduced rotation outputmeans, and said first clutch is engaged; wherein, in fourth speedforward, said first clutch and said second clutch are engaged; wherein,in fifth speed forward, reduced speed rotation is input to said firstrotary component from said reduced rotation output means, and saidsecond clutch is engaged; wherein, in sixth speed forward, said secondclutch and said first brake are engaged; wherein, in first speedreverse, reduced speed rotation is input to said first rotary componentfrom said reduced rotation output means, and said second brake isengaged; and wherein said automatic transmission provides six forwardspeeds and one reverse speed.
 27. An automatic transmission according toclaim 24, comprising a pair of said first planetary gear units eachcomprising a first sun gear, a second sun gear linked to said first sungear, a first carrier meshing with said first sun gear, a second carriermeshing with said second sun gear, a first ring gear linked to saidsecond carrier, and a second ring gear meshing with said second carrier;wherein said first rotary component is said second ring gear and isfixed by engagement of said first brake; wherein said second rotarycomponent is said first sun gear which receives input of rotation ofsaid input shaft by engagement of said first clutch; wherein said thirdrotary component is said second carrier and said first ring gear whichreceive input of rotation of said input shaft by engagement of saidsecond clutch, and which are fixed by the engagement of said secondbrake; and wherein said fourth rotary component is a first carrierlinked to said output member.
 28. An automatic transmission according toclaim 27, wherein, in first speed forward, said first clutch and saidsecond brake are engaged; wherein, in second speed forward, said firstclutch and said first brake are engaged; wherein, in third speedforward, reduced speed rotation is input to said first rotary componentfrom said reduced rotation output means, and said first clutch isengaged; wherein, in fourth speed forward, said first clutch and saidsecond clutch are engaged; wherein, in fifth speed forward, reducedspeed rotation is input to said first rotary component from said reducedrotation output means, and said second clutch is engaged; wherein, insixth speed forward, said second clutch and said first brake areengaged; wherein, in first speed reverse, reduced speed rotation isinput to said first rotary component from said reduced rotation outputmeans, and said second brake is engaged; and wherein said automatictransmission provides six forward speeds and one reverse speed.
 29. Anautomatic transmission according to claim 1 providing six forward speedsand one reverse speed, and wherein in fifth forward speed said firstclutch and said second clutch are engaged.
 30. An automatic transmissionaccording to claim 29, wherein said first planetary gear unit is amultiple type planetary gear unit comprising a first sun gear, a longpinion which meshes with said first sun gear, a short pinion whichmeshes with said long pinion, a carrier rotatably supporting said longpinion and said short pinion, a second sun gear meshing with said shortpinion, and a ring gear meshing with said long pinion; wherein saidfirst rotary component is said second sun gear and is capable ofreceiving input of the reduced speed rotation of said reduced speedrotation output means; wherein said second rotary component is saidcarrier which receives input of rotation of said input shaft byengagement of said first clutch, and which is fixed by engagement ofsaid first brake; wherein said third rotary component is said first sungear which receives input of rotation of said input shaft by engagementof said second clutch, and which is fixed by engagement of said secondbrake; and wherein said fourth rotary component is said ring gear linkedto said output member.
 31. An automatic transmission according to claim30, wherein: in first speed forward, reduced speed rotation is input tosaid first rotary component from said reduced speed rotation outputmeans, and said first brake is engaged; in second speed forward, reducedspeed rotation is input to said first rotary component from said reducedrotation output means, and said second brake is engaged; in third speedforward, reduced speed rotation is input to said first rotary componentfrom said reduced speed rotation output means, and said second clutch isengaged; in fourth speed forward, reduced speed rotation is input tosaid first rotary component from said reduced speed rotation outputmeans, and said first clutch is engaged; in fifth speed forward, saidfirst clutch and said second clutch are engaged; in sixth speed forward,said first clutch and said second brake are engaged; and and wherein, infirst speed reverse, said second clutch and said first brake areengaged; whereby six forward speeds and one reverse speed are provided.32. An automatic transmission according to claim 1 wherein said firstclutch is located on the side of said first planetary gear unit axiallyopposite said reduced speed rotation output means.
 33. An automatictransmission according to claim 1, wherein said first clutch engages ata relatively low to medium speed.
 34. An automatic transmissionaccording to claim 1, wherein said second clutch engages in reverse. 35.An automatic transmission according to claim 1, wherein said firstclutch comprises first friction plates which, at their radially inwardends, are splined to a member linked to said second rotary component, afirst drum member integral with a hydraulic servo, second frictionplates splined to an inner surface of said first drum member andintermeshed with said first friction plates, a first piston member forpressing said intermeshed first and second friction plates, and a firsthydraulic servo having a first oil pressure chamber formed by sealingbetween an inner cylindrical surface of said first piston member andsaid first drum member; and wherein said second clutch comprises thirdfriction plates which, at their radially inward ends, are splined to amember linked to said third rotary component, a second drum member whichis integral with an oil pressure servo and which is splined to fourthfriction plates intermeshed with said third friction plates, said seconddrum member being radially inward of a member linked to said secondrotary component, a second piston member for pressing said intermeshedfriction plates, and a second hydraulic servo having a second oilpressure chamber formed by sealing between an inner cylindrical surfaceof said second piston member and said input shaft, and between an outercylindrical surface of said second piston and said second drum member.36. An automatic transmission according to claim 1, wherein said outputmember is disposed axially between said first planetary gear unit andsaid reduced speed rotation output means.
 37. An automatic transmissionaccording to claim 1, wherein said output member is disposed axiallybetween said first planetary gear unit and said second clutch.
 38. Anautomatic transmission according to claim 1, wherein said reduced speedrotation output means is a double pinion, speed reducing, secondplanetary gear unit; and wherein said first and second planetary gearunits and said output member are coaxial with said input shaft.
 39. Anautomatic transmission according to claim 1, further comprising adifferential unit for outputting rotation to drive wheels, and a countershaft unit for engaging said differential unit, wherein said outputmember is a counter gear meshing with said counter shaft unit.